Set Rhythms
The best way to gain control of rhythms and timing in your playing is to take one subdivision of the beat at a time (in this case, swing 8ths) and learn to play them in any part of the bar. A great way to do this is to use a set rhythm and improvise melodically. First, try improvising over a Blues progression using constant eighth notes only. Don't use any rests or faster bits. It's alright to use grace notes however because they have no written time of their own. Here is an example.
After you have tried constant eighth notes, the best thing to do is to play your 8th notes on selected beats only, as shown in the following example which uses only the first beat and the "let" part of the first beat. The rest of the bar is silent. Notice how these two notes are still enough to make a theme.
The solo makes sense if you use your ears carefully in terms of what notes you play against what chords. Always try to have a definite idea to work around rather than just playing random notes. After mastering the first beat you could move onto the other three possible beats in the bar.
