My Paintballs Are Shooting Like Crap...

It's probably not a good idea to store your leftover paintballs from your last outing in the trunk of your car.  The best way to think of it is to compare paint to a person.  If you think an environment would make you uncomfortable, then it's more than likely not good for paint either.  Excessive heat or cold will ruin paintballs within hours, while paint that's properly stored in a cool, dry place like your room (assuming you can clear a space in there!) will last for months and months if properly rotated.  By rotating, we mean literally moving the bags of paintballs around to keep the fill from settling to one side and to prevent dimples from forming.  While the dimples on a golf ball help it fly better, on a paintball it just doesn't work.  Other reasons your paintballs may not be shooting well are goop in your barrel and/or breech of your paintball marker.  Once again cleanliness is next to godliness, so make sure your marker and paintball gun barrel are clear of paint and clean your paintball marker often and thoroughly.