The Marxists Internet Archive hosts an interesting short essay by Amílcar Cabral.
The website states that the essay is sourced from Revolution in Guinea (London, 1964), but the pre- and post-script to the essay explain that it was assembled together from extracts taken, already in English, from Basil Davidson’s The Liberation Of Guiné: Aspects Of An African Revolution (1969). I was unable to find that exact book, but Davidson released an expanded edition under the title No Fist Is Big Enough to Hide the Sky: The Liberation of Guinea-Bissau and Cape Verde, 1963-74 (1981), and this volume was available online.  It reveals that the individual excerpts were interspersed as part of a first-hand narrative, spanning several different chapters. The ultimate reference document is the “1965 General Directive” authored by Amílcar Cabral serving as the General Secretary of the African Party for the Independence of Guinea and Cape Verde (PAIGC).
@estranjohelped me track down an original version of this document in Portuguese at the University of Lisbon archives. 
I’ve matched the English excerpts back into the original Portuguese, reordered it so that adjacent segments remain together, and expanded it with some extra excerpts I found interesting. Please refer back to the original source before using this document as reference!
Always bear in mind that the people are not fighting for ideas, for the things in anyone’s head. They are fighting to win material benefits, to live better and in peace, to see their lives go forward, to guarantee the future of their children. 
Our Party and the popular masses of Guinea and Cape Verde have been actively preparing in all necessary areas to unleash armed struggle in the Archipelago. We must do this, but we must do it under the best conditions, taking into account the characteristics of armed struggle particular to this very special geographic environment. We must move fast but without taking shortcuts, without opportunism, without the kinds of enthusiasm that make us lose track of concrete reality. It’s better to start the armed struggle after an apparent delay, but with guarantees of continuity, than to begin it too early, or at any other time, without having secured all the conditions that guarantee the victory of our people.
We should recognise as a matter of conscience that there have been many faults and errors in our execution thus far, whether political or military. An important number of things we should have done we have not done at the right times, or not done at all.
In various regions — and indeed everywhere in a general sense — political work among the people and among our armed forces has not been done appropriately: responsible workers have not carried or have not been able to carry through the work of mobilization, formation and political organisation defined by the party leadership. Here and there, even among responsible workers, there has been a marked tendency to let things slide, to fail to accomplish the tasks set out by the Party and the struggle, and even a certain de-mobilisation, which has not been fought and eliminated.
On the military plane, many plans and objectives established by the Party leadership have not been achieved. With the means we have, we could do much more and better. Some responsible workers have misunderstood the functions of the army and guerilla forces, have not made good co-ordination between these two and, in certain cases, have allowed themselves to be influenced by preoccupation with the defence of our positions, ignoring the fact that, for us, the best means of defence is the attack, the offensive, and the constant development of our armed struggle.
Furthermore, as a result of the lack of effective political work within the armed forces, a certain mania for “militarism” has begun to appear and it has led some combatants and even some officers to forget that we are armed militants and not militarists. This tendency must be urgently fought and eliminated within the F.A.R.P.  In other aspects of our struggle (education, health, commerce, etc.) mistakes have also been made. These, however justified by our lack of experience, should nevertheless be eliminated by any means necessary. 
If ten men go to a rice field and do the day’s work of eight, there’s no reason to be satisfied. It’s the same in battle. If ten men fight like eight; that’s not enough. One can always do more. Some people get used to the war, and once you get used to a thing that’s the end. You have a loaded gun, but merely walk around. You hear the motor on the river and you don’t use the bazooka that you have, so the Portuguese boats pass unharmed. Let me repeat: one can do more. We have to throw the Portuguese out. 
In the liberated areas, we must do everything possible to normalise the political life of the people. Section committees of the Party (tabanca committees), zonal committees, regional committees, must be consolidated and function normally. Frequent meetings must be held to explain to the population what is happening in the struggle, what the Party is endeavouring to do at any given moment, and what the criminal intentions of the enemy may be. 
In regions still occupied by the enemy, we must reinforce clandestine work, the mobilisation and organisation of the populations, and the preparation of militants for action and support of our fighters. In particular, in urban areas (cities and towns), promote the strengthening of the militants’ work through slogans, re-establish any suspended connections, and prepare Party members — especially workers — for action against the enemy, and for defense of our material gains. 
Develop political work in our armed forces, whether regular or guerilla, wherever they may be. Hold frequent meetings. Demand serious political work from political commissars. Start political committees, formed by the political commissar and commander of each unit in the regular army. Oppose tendencies towards militarism and make each fighter an exemplary militant of our Party. 
Reinforce political work and propaganda within the enemy’s armed forces. Write posters, pamphlets, letters. Draw slogans on the roads. Convey to enemy forces the political goals of our Party. Establish cautious links with enemy personnel who want to contact us. Act audaciously and with great initiative in this way, in order to lead these enemies to serve our Party and our struggle, against the criminal colonial war. Do everything possible to help enemy soldiers to desert. Assure them of security so as to encourage their desertion. 
Carry out political work among Africans who are still in enemy service, whether civilian or military. Persuade these brothers to change direction so as to serve the Party within enemy ranks or desert with arms and ammunition to our units. But hit hard and take out all of those who consciously betray our people, all of those who advocate for taking up arms on the side of the enemy, against our Party and our people. 
Create schools and spread education in all liberated areas. Select young people between 14 and 20, those who have at least completed their fourth year, for further training. Oppose without violence all prejudicial customs, the negative aspects of the beliefs and traditions of our people. Get every responsible and educated member of our Party to work daily for the improvement of their cultural formation. […] 
Oppose among the young, especially those over 20, the mania for leaving the country so as to study elsewhere, the blind ambition to acquire a degree, the inferiority complex and the mistaken idea which leads to the belief that those who study or take courses will thereby become privileged in our country tomorrow. […] But also oppose any ill will towards those who study or wish to study — the complex that students will be parasites or future saboteurs of the Party. 
Educate ourselves, educate other people, the population in general, to fight fear and ignorance, to eliminate little by little the submission to nature and to the natural forces which our economy has not yet mastered. Convince, little by little, the militants of the Party in particular, that we shall end by conquering the fear of nature, and that man is the strongest force in nature. 
Demand from responsible Party members that they dedicate themselves seriously to study, that they interest themselves in the things and problems of our daily life and struggle in their fundamental and essential aspect, and not simply in their appearance. Get them to work every single day on their knowledge, their culture, and their political formation. Convince everyone that no one can know without learning, and that the most ignorant person is the one who claims to know without having learned. Learn from life, learn from our people, learn from books, learn from the experience of others. Never stop learning.
Responsible members must take life seriously, conscious of their responsibilities, thoughtful about carrying them out, and with a sense of camaraderie based on the fulfillment of work and duty. Nothing of this is incompatible with the joy of living, or with love for life and its amusements, or with confidence in the future and in our work. 
Never has it been more certain that our victory depends principally on our own actions. The enemy also knows this, and is every day more de-moralized, more desperate in their efforts to hold out. But they know that their days are numbered, and, therefore, the gravity of their crimes against our people and our property and our wealth will only increase.
We must, therefore, realizing the favorable prospects of our struggle, study each problem in depth and find for it the best solution. We must think in order to act, and act in order to think better. We must, as always, face the present and the future with optimism, but without losing awareness of the realities, the particular characteristics of our struggle. We must always keep in mind the watchword of our Party: “Hope for the best, but prepare for the worst.” 
We must practice revolutionary democracy in every aspect of our Party life. Every member must assume their responsibilities with courage, demanding from others a proper respect for their work and properly respecting the work of others. Hide nothing from the masses of our people. Expose lies whenever they are told. Mask no difficulties, mistakes, or failures. Tell no lies, and claim no easy victories. 
Basil Davidson, 1981. No Fist Is Big Enough to Hide the Sky: The Liberation of Guinea-Bissau and Cape Verde, 1963-74. [web] ↩
Amílcar Cabral, 1965. «Palavras de Ordem Gerais: do camarada Amílcar Cabral aos responsáveis do Partido». [web] ↩
IV, 2. ↩
Revolutionary Armed Forces of the People. ↩
This comes from a different source than the rest of the excerpts, a transcribed speech. See: Gerard Chaliand, Lutte Armee en Afrique, Maspero, Paris, 1967, pp. 50-1. The Portuguese in this case is translated back from English. — R. D. ↩
II, 1. ↩
II, 2. ↩
II, 3. ↩
II, 4. ↩
II, 5. ↩
VII, A. ↩
VII, 5. ↩
VII, 8. ↩
VII, 9. ↩
VIII, 4. ↩