Stijn, all these suggestions are excellent but perhaps they aren't addressing the root of your problem. Here's some information about soloing that may help. There are three ways to solo:
- Play the exact melody
- Vamp on the chord structure of the song and basically avoid the melody
- A combination of 1 and 2
I use the third method most of the time. The advantage is, you only need to learn a small amount of the actual melody. You play some of the melody to start and then just vamp on the chords in between. For beginners, the chord vamping can be just playing the chords in time with the music. Over time, you'll learn variations of the chords that adds a little more sophistication to your solo. The big advantage of this method is, you sound like you know how to solo but you don't cause the listener to lose track of your song, which often happens in method two.
The most difficult method, which you're currently trying to do, is the first one because you must play the song virtually note for note. What makes it the most difficult is the fact that you're not allowed to make any mistakes. There's no freedom. Method three let's you wander outside the lines a bit or a lot.
*Bonus information*The great players like Ray Charles, Diana Krall, and Oscar Peterson almost always use method three.
