1. Dont get attached to your loot! You will always lose it at some point. Remember that your loot is temporary.
2. Dont put all of your eggs in one basket. Spread your loot out amongst several hidden stashes. Putting it all in one spot is like giving it away.
3. Bases attracts attention. The walls stick out and its very very easy to break in. Avoid building bases to store your loot. I understand some build for fun, but remember to have a second stash to fall back on.
4. Oil barrels can be dropped under water. This makes a great Little stash that nobody will expect.
5. Avoid walking on roads and crossing open fields. Being in the open makes you an easy target. Always stick to the trees and keep your head on a swivel.
6. Carry only the essentials. Avoid a cluttered inventory and spread your supplies amongst different pieces of clothing so when you eventually get shot everything doesn't get ruined.
7. Trust nobody.
8. Learn the entire map. This will give you an edge over an opponent.
9. Safety in numbers. Although its risky trusting someone, being part of a group gives a significant advantage in a fight.
10. Dont be afraid to die. Acceptance of death will calm you down in a fight. Its not a big deal if you die.
11. The sun always sticks to the southern portion of the sky.
12. Rags are superior to bandages.
13. Duct tape fixes everything. Always keep a roll on your character.
14. Never stand still for long. always keep moving.
15. Use the right weapon for the right job. Keep in mind the max effective range of the guns you are carrying. Only shoot when you know you can hit.
16. Lear the advantages and disadvantages of the guns you are using. Practice and fights will teach you.
17. Dont be afraid to get in fights. You need to fight to get better at fighting.
18. Stamina is important. having more stamina than you opponent gives you a huge advantage.
If anybody else has some tips, write them below.