- Get the DLC which contains parachute thrusters - they make getting around a hell of a lot easier, but they don't cheapen the game.
- Also get the mod which enables parachute thrusters by default, so that you don't have to re-buy them every time you die.
- The base game has a small set of about 6 upgrades (associated with the last mission) and a single destructible water tower that are bugged and do not spawn. This makes 100% completion impossible without the use of mods.
- Other than that, just get whatever mods you want to change whichever gameplay mechanics you don't like.
- Never buy what you can steal. Unless you've modded in free Black Market or Infinite Funds. In that case, knock yourself out.
- Don't bother scouring every village and base for 100% of every item. There's far more upgrade parts and money than you'll ever need, anyways.
- If you go to the PDA so that you're looking at the map of Panau, you can middle-click (On PC) to set a waypoint - I have no idea what key it is on the consoles. This will give you a marker in-game, and if you're driving, arrows on the road in the style of a sat-nav.
- Learn the art of grapparasailing. Get chuteborne, fire the grappling hook at a patch of ground in the direction you want to go, shift your weight back (S) enough to convert the pull into forward motion but not too much so that you end up with your face towards the sky, fire again. Practice it, it turns into second nature.
- Blow up anything that's red and white.
- Combat is surprisingly lethal. Pick a weapon to level up; I suggest SMGs or assault rifles. Use it.
- When assaulting bases, try hit and run tactics. Sneak around the side, steal a vehicle, cause chaos, sneak off, cause more chaos.
- Cause chaos. Killing dudes, collecting collectables and blowing up red-and-white things all increase chaos, which will unlock storyline and faction stronghold missions.
- Do a couple story missions right away. After meeting all the factions, you can do stronghold missions to unlock side missions.
- Clear out towns/military bases/shipyards/etc. Most of the destructible items and collectibles are located in these. They're labeled on your map, although they're just a colored dot if they haven't yet been discovered.
- There's a little signal strength indicator up by your minimap. It shows proximity to upgrades. Pay attention to it to find weapon, vehicle and health upgrades.
- The black market will airlift you to any discovered location for free, from anywhere.