A very important thing to do for your jazz chops is to put a group of
musicians together to play standards and jazz tunes with. It doesn't have
to be a full band, it can be just you and one other instrument, the point is
to make a habit of playing jazz with a person or persons on a regular basis.
If this is completely unavailable to you, make or buy play along recordings
to practice with. These are good for isolating a song you are having trouble
with and repeating it until you are more familiar with it,
you can also experiment with different ideas against the chord changes
without fear of sounding bad in front of another musician.
Don't rule out playing jazz with live people though, it can give you instant
feedback which can fuel ideas of what you need to work on while practicing by
yourself. It is good for honestly judging your ability because some things
that seem "nailed" in the practice room (like double time solos, swing feel,
tasteful use of vibrato, and comping behind other players) are much harder
with the pressure of playing in front of other musicians' ears and opinions.
If you make a habit of this, your confidence level for performing jazz in
public will increase remarkably.
While practicing by yourself, mostly practice what you can't do yet until you
can do it and then move on to the next thing you can't do. Many people who
improve slower than they would like are repeating what they are familiar with
too much, leaving little room for experimenting with new techniques.
These are just ideas, not a "system" but they should help.
Brian Oates