I realize this has probably been answered a thousand times in the course of GT history, but I figure as long as you folks have got the knowledge, I might as well ask it again.

How do you put scales to use? I mean, I'm willing to learn scales and stuff if it helps me play better, but I just haven't a clue how to put them to use in constructing solos and whatnot. I understand a little bit of theory (I understand the modes somewhat), but isn't it true that the notes in a scale can be played along with other notes? If so, what do the notes on a scale mean? And also, how do you know which scale(s) to use when improvising?