I can just "feel" where the next note should be. Other solos are completly purplexing. Even looking at the tab and playing it at half speed it just never makes any sense-why would you jump from the 5th fret on g to the 15th on a-or something similar-and then back again...
I find that listening to a song over and over and not thinking about playing it-but listening to where the music goes gets it into my mind enough to get it to where I can whistle it. When performing, I guess I don't think-I just know-
I think were it starts and where it ends only. Usually the middle just fills itself in. Could be magic, but it is probably just hours and hours of practice.
When improvising-just play what you know and feel. Play different styles-a little blues, a little country, and little classic rock. Someday, you will be able to mix them up within the same solo and be a star...