This guide by Prima Games will give you the locations of some of the fun things to do (STUNT JUMPS!!11) and find some of the hidden items to help you build cool toys.
GTA 5 Cheats
Granted, using cheats to beat Grand Theft Auto 5 is, well, cheating, but it's hard to ignore all the benefits that come from these codes during gameplay. Spawn a Buzzard Attack Helicopter and pummel enemies with rockets, instantly obtain a Give Parachute while in the air or load Explosive Rounds to gain the edge in a gunfight. You can even goof around with the Drunk cheat and change the weather; perhaps the best GTA 5 cheat is the one that lowers your wanted level. Regardless of which one is your favorite, you probably didn't take full advantage of these codes the first time around.
Here's a list of the cool GTA 5 cheats.
Finding All 50 Apaceship Parts
Yup, Rockstar scattered 50 of these UFO parts throughout Los Santos and Blaine County. Finding them all will take some time, but the reward is well worth the trouble. In addition to exploring every corner of the game and taking in the sights, you'll unlock the Space Docker, a cool dune buggy that makes out of this world sounds. But first, you'll need to beat the Fame or Shame Mission and then visit Omega the Hippie. Far out, dude!
GTA 5 Hunting Challenges
Trevor is one of the best characters in GTA 5. The beer-drinking, foul-mouthed criminal isn't afraid to enjoy his favorite pastimes, hunting being one activity. Meet up with Cletus in Blaine County and earn rewards for sniping boar, elk and coyotes. Just be careful of mountain lions.
Read Prima's free GTA 5 Hunting Guide for more info.
Click here for more cool stuff you missed in GTAV, like stunt jumps!