1. google "ps3 safe mode". you'll want to "restore the file system" and NOTHING else. this get's rid of all your corrupt data, so if you have a bad save expect it to be gone.
2. turn off the autosaves. I know, it sucks. but you don't want your game to crash while it's making a quick save. that would suck. just make sure you save everytime the autosave would, or shortly after. the game will occasionally make an autosave before key moments, so don't be surprised to find one if you do.
3. create new data EVERY time you save. just delete your old saves you don't want before you start up the game next time to clear some space.
4. disable the auto killcam that happens when killing someone outside of VATS occasionally. the default should be set to "cinematic". set it to off.
5. while in the settings turn the music off. this is the in-game music that always plays. when spotted by an enemy, it will get more dramatic, which requires the game to suddenly load an audio file while trying to load simultaneous things at once(enemy AI, textures, anything your doing).
6. Also set the radio to off. just slide the thing all the way to the left, i think that just disables the function altogether. this applies to the tip above, as well. (courtesy of DaftenDirekt)
7. try to avoid using VATS in tight spaces (where your player is confined) and definetly avoid using lever-action firearms in VATS (cowboy repeater). it sometimes works, but othertimes you'll find your player just standing/crouching there while you get attacked, and eventually die.
8. changing your HUD(heads-up display) colour to something other than the default orange can improve gameplay(courtesy of oldsnake90)
EDIT: 9. A couple of players noticed that playing offline (not signed-in) can lower the risk of freezes(courtesy of PlayDude77). you may just want to disable the internet connection entirely. (XMB-> Settings-> Network Connection Settings. should be near the bottom)
10. I've seen some posts that say if your game is freezing up a lot exit back to the XMB and reload it. I did this once and where the game is supposed to appear it said "corrupt data" and wouldn't/couldn't launch it. so you may want to try this at yor own risk. if the same happens to you, restore the file system in safe mode again.