After Game "Briefing"
Finish Just Cause, then start a new game. Don't save then load your normal Profile. You should have a briefing on your Extraction list. It will get you to the first beach in the game.
After you kill the man on the boat and finish the mission, you will get the agency jeep.
Bald Eagle Persuader Boat
There is a boat that looks oddly like the Gungan submarine in Star Wars Episode 1. It is called the Bald Eagle Persuader.
It travels ridiculously fast on water. If you drive it in a straight line for long enough it takes off and wings grow from the side. When you land it, wheels pop out underneath. It is very difficult to control. It appears about one in every ten visits to the mansion near a safehouse. Note: it cycles in this order: sea, air, land. If you go from the air to the sea it will just explode.
Boarding The President's Plane
When you are flying the jet in the final level, fly over the top of the plane. Try to hover over one of the wings or the front of the plane (recommended). Quickly jump out of the jet and let go. If done correctly, a 'Jump to vehicle' icon will appear. Quickly press A and he will grab on. You will immediately appear in the plane.
After level 2 there are territories you can take over. Once you have done about three of them you will get the grapple hook.
When you get your grapple hook fire it at a passing or attacking helicopter. Then, just reel your self in.
High Sky Dive
For this trick you will need the grapple, and be in a place where you can use heavy drop. Use heavy drop on any vehicle you want, but when the helicopter arrives grapple it. The helicopter will ascend really fast. In just 20-30 seconds youre above the clouds! Let go whenever you want too, and enjoy the fall!
Equip a weapon and press RED to jump. Immediately upon jumping, change weapons. This will cause the jumping action to be repeated, so you can double jump. In this second jump, if you change weapon again, you will jump another time. You can repeat this as much as you want.
This lets Rico climb any building or gap, provided you start with a forward (not stationary) jump. If you don't manage to do the trick, rico will simply fall. If you do the trick too quickly Rico will either stay still or go horizontal. It is best to alternate between two weapons rather than to cycle along, and to have more than 2 weapons in case you change to unarmed or don't change weapons at all.
This trick allows you to get huge base jumps such as my best, 2129m (twice the achievement record). Very useful technique if you are stuck in the jungle, miles away from any road.
Taking Over Sites
Use the following trick when you are taking over a village with the guerrillas. Ignore most of the enemies and charge towards the roadblock the government has up. Destroy it using grenades, a rocket launcher or timed explosives. Do this to each one, and the 'Capture enemy flag' objective will soon appear. Rush to it and press A to conquer that area. For other villages without roadblocks, such as the towns when a police car with a turret on the back appears, go in it. One of your teammates will also enter. Drive down street and your partner will gun down everyone. Then, capture the flag when instructed. Do not open fire on anyone on your team or they will kill you.