-Never sell a weapon or armor
-Always reload around half clip
-Often avoid instance based combat (where the battle cuts away to a separate area, such as with random encounters and onscreen RPG foes) but always engage every enemy in action games.
-Pick up every item I see, despite my hesitance to use them (this also includes buying from traders to keep a certain number of healing items always on hand)
-Always believe a room has a reason if it's empty (unless it's along the way to the next objective)
-Break all barrels/boxes
-Crouch in shooters where the environment is dark
-Never let an enemy escape
-Avoid using magic until I'm able to properly handle 10 or so in a row
-Absolutely go out of my way for avatar changing items (outfits, strange weapons, skins, etc.)
-Constant free heal (for example, if I take only 5 damage when I have 6000 health when I walk outside the health restoring save point, I will go back in, even if the enemy that did it will respawn)
-Save twice
-Stay away from long range weapons in action games
-Forget to block... a lot.
-Curse at a character for screwing up a jump or moving the wrong way
-Follow the lights
-Always dash if I'm able
-Accept any side quest, even if I have no want to follow through (except when it takes over the main quest)
-Go crazy after saving in any sandbox game
-Play as a good character unless I just decide to be bad all the way through (though this was brought about by my experience with KotOR where being bad lost you around half your party, even if I didn't use those members, and in the second where you lose 2 Jedi by going evil, so this is all Bioware's fault).