There is a boat called the Bald Eagle Persuader that highly resembles the Gungan submarine in Star Wars: Episode 1. It randomly appears at the mansion near a safehouse in about one out of every ten visits.
Steal two cars, then face one forward and park the other one sideways in front of the car. Get into the stunt position to have the "B Jump to Roof" option be on top. Just press B(20) to get the achievement.
Equip a weapon and press B to jump. Right after jumping, switch 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 many times as desired, allowing Rico to climb any building or gap, provided you start with a forward (not stationary) jump. If you do not manage to do the trick, Rico will simply fall. If you do the trick too quickly, Rico will either remain still or go horizontal. It is best to alternate between two weapons rather than to cycle along, and to have more than two weapons in case you change to unarmed or do not change weapons at all. This trick allows you to get huge base jumps and is thus a useful technique if you are stuck in the jungle, miles away from any road.
-When 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 to make the "Capture enemy flag" objective 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 your team or they will kill you.
-Use your heavy drop in your PDA when taking over Guerrilla and Rioja sites. Select the truck and start shooting your way through the entire thing until you have to take the flag at a Guerrilla site, or kill the head honcho at a Rioja site.
-When flying the jet in the final level, fly over the top of the plane and 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. Immediately press A and he will grab on. You will then appear in the plane.
-On the last mission you will be in a jump jet with other jets following you. Go towards the Presidential plane, fly straight into i,t and bail out above the wing. If you touch the plane, you board it. When on board, kill the black hand and go towards the door. You will begin falling . Fly towards Mendoza and tap A to start a cutscene where Rico puts a bomb on Mendoza. Mendoza explodes, then Rico says "He always wanted to spread his spirit; and now there's pieces of him everywhere!". You will respawn at Mendoza's mansion and the game will end.