when i first started trying to do my own solos, i took a very simple and practical approach. i'd record a lengthy recording of the chord progression that i wanted to solo over, so that i'd have time to experiment, and wouldn't have to mess with rewind right when i had an idea starting to develop.
someone mentioned melody. that's the way to go, it gives you some kind of base to build on. come up with a simple melody, it doesn't have to be fantastic, just as long as it fits, and/or is suitable to your tastes.
try different variations of the melody. learn to play the melody an octave higher, and lower. play one variation, use one of your scale runs to get you an octave higher, and play a different variation of the same melody.
the melody gives you a comfortable place to go back to, where you know it will fit. in your warping and twisting of the melody, you will hear/find/create other licks and you may actually have to pause the tape to get them just how you want them.
this helps to get the "hear it in your head" thing going as well.