You'll need to practice a lot. Also, some theory could help you develop your style.

First and most important of all, remember that melodic content and feeling are the things you look for. Well, with that said, here's something for you to explore:

Try your hand at modal improvisation. For example, you have a progression that is diatonic to C Major, such as:

CMaj7 Am7 FMaj7 G7

You could solo using only the C major scale over it and it will sound good, but you can also try playing certain mode over each chord to make it sound more interesting.

For example:

CMaj7: you could switch between C major and C Lydian (C D E F# G A B)
Am7: Maybe A dorian (A B C D E F# G) or A phrygian (A Bb C D E F G)
FMaj7: F Ionian (F G A Bb C D E)
G7: G myxolydian to avoid the loss of the dominant feeling, but you could also use Lydian b7 (G A B C# D E F) or Myxolydian b6 (G A B C D Eb F) to give it a minor cadence feeling.

Both Lydian b7 and Myxolidian b6 are taken from the melodic minor scale. You could also use Myxolidian b2 b6 (G Ab B C D Eb F), but as it comes from the harmonic minor, it has a very characteristic sound (because of the 1 1/2 tone jump from Ab to B) that makes it somehow awkward to use. There are way more options for each chord, but I think with that it's enough to keep you entertained for a while.

I know it seems as a lot of clutter, but if you analyze it, there's just 1 note difference between the options listed and the C major scale. Experiment and find your own way to apply this (or ditch it and shred till not even you know what you're playing :P).

Also, if the sound of certain mode or anything doesn't convince you, you can always make up your own, and don't be afraid of playing notes that are not in certain scale, if you find a way of getting them in the right place, they can sound really cool.