Arguably the most entertaining thing to do in Far Cry 3 is exploring the islands and taking outposts. You can approach them from any angle and take everyone out anyway you like, every encounter is different.
To take an enemy outpost you must kill all the guards that are stationed there. You will gain 500xp for taking each one with 50xp bonus if no alarms are triggered. What you really want is the undetected bonus, if no-one spots you before you take them out you will be awarded a whopping 1500xp which needless to say can be rather handy when trying to unlock new skills.
When approaching an enemy camp find a good vantage point and take out your camera to tag all the enemies. The best weapons to use for this objective is anything with a silencer or the bow. Personally I carry a silenced sniper rifle and a recurve bow. Use the sniper rifle to take out any guards on lookout but be careful to make sure no-one will see the body. These guys are most likely to spot you at a distance, so if it won’t compromise your presence then go for it. As you move closer to the base try picking out lone guards quickly and quietly and dragging there body to some cover (assuming you have the skill that allows you to drag the body). If there are guards grouped together then you’re going to have to either kill them in rapid succession or lure them away one by one and stick a knife in them while no-ones looking. If you decide to take them out quickly make sure you’re using a silenced automatic weapon such as an SMG, otherwise use the rock throwing function to lure the guards closer to you and then silence them. If you can get close to an alarm without much risk of being spotted the do so, disable it so that if the shit hits the fan, the pirates won’t be able to call for help.
Another way to take out enemies without being spotted is to use any wildlife the guards may have locked up against them. Simply shoot the door off the cage with a silenced weapon and watch the carnage unfold. This will often make your job easier as the animal can take out several guards. In one encounter as I approached an outpost I found myself face to face with a bear, so instead of killing it I ran towards the outpost and just as it was about to maul me I used the animal repellent syringe. The bear then ran into the outpost and started causing havoc, and just to help things along I shot the door off a cage and let a tiger loose. I sat on the sidelines and never fired another bullet, the bear and the tiger killed everything! Easiest, most satisfying 1500Xp I’ve ever earned!
This is just a few ways to do it, there are so many different options and with 34 outposts to take you have the ability to switch up your tactics. Use molotovs to start bush fires, shoot the red barrels inside the outposts for hilarious results, set up traps with mines and C4, or just go in guns blazing! The possibilities are endless!