Try to buy the camouflage as fast, as possible. This is the most costly item in the game (45 diamonds), but he's worth his price. You can use him especially in the high grass. You will be invisible even for the closest enemies. You should of course be immobile when the enemies are a few steps from you and crouch. The camouflage is most effective if you have silenced weapon. The camouflage is still active, so you don't have to activate him manually.
After a short while you will notice, that using containers for weapons is very good idea. Weapons placed in containers are available in all hideouts.
Our hero has malaria. The sickness is influencing mainly on fatigue during the run. To eliminate this symptom, our hero has to swallow from time to time the special pills. Unfortunately they are rare. You can obtain them only by completing mission for the faction of the Underground. To complete such missions, you have to delivering the documents to particular places. If you do this, the fugitives will give you the pills. If our hero won't swallow any the pill for the longer time, he will pass out and wake in the city. This can happen even during the mission, so you should have the supply of this medicine.
Heavy used weapons will be jamming quite often than weapons in good condition. You should invest in reliability upgrades.
If you will learn how to fix the engine you will be able to fix him quite better than without this ability. Of course the repair will be possible only for these engines, which are specified by bought ability.
In the big cities, you can find several suitcases with diamonds. In Leboa-Sako these suitcases are located in guarded - red zones. To obtain them, you will have to be very patient and be good in sneaking or fighting with whole city. Fortunately you can obtain few suitcases without fight. At the end of the first act, the journalist will tell you that you should help the pastor or your friends in Mike's bar. You can then search the Pala. The city will be abandoned.
If you want to have fastest access to the more powerful weapons, you should take the jobs from the owners of the shops with weapons and attack indicated convoys. Bellow you will find the table with information, what is unlocking particular attack:
Grenade Launcher M-79
Mortar Type 63
Rocket Launcher Carl G