Remember that when a bot spots you, it will more often than not follow you and shoot. Also remember that bots sometimes stay in place not doing anything, but don't even think about getting close then. I've had times when they turn back and kill you quickly even with Mega Buster.
A trick to kill following bots is to lure them into following you and stop half covered by a corner. Get out a ripping weapon like Metal Blade or Yamato spear or fast firing weapons with stopping power like Needle Cannon, and shoot. They'll just eat it and die most of the time. This is sort of advanced though and new players shouldn't attempt it unless they're practicing to become better.
Now, we need a section about what to do when you're the leader of the bots, and such.