Dude, find songs with slow mid eights or half time sections, or long solos. Then just jam over it. Learn a small part of a scale and just mess around with the notes in it.

Heres G major

e--12------14--15
b--12--13------15
g--12------14----

the 12th fret of the 3rd string is the root in the above case, moved the pattern up two frets and its then A major.