It's important to develop a personal practice routine. Consistency is the key to progress in any endeavor. 20 minutes a day will yield better results than 2 hours once or twice a week.
In addition, it is imperative that you perform in some type of ensemble : A Jazz quartet, quintet, etc. A Jazz Big Band A chamber ensemble. Orchestra. Concert Band
A musician is the sum total of his experience. The more styles and varieties of music you perform - the more you will have to draw on for your improvisation.
Breathing
Breathing technique is essential for woodwind and brass players. Upper body strength and a strong diaphragm are essential. Swimming, jogging and other activities that provide a cardio workout are encouraged. Crunches and situps will strenghten the diaphragm and give greater control of the airstream. Yoga, specifically Pranayama is ideal .
Memorization
Regardless of what genre of music you perform, you must build a repertoire. The memorization of songs/tunes, riffs, licks and classic band arrangements is necessary to play Jazz.
If you are attempting to memorize a written piece : 1. Read the piece through a few times. 2. Focus on one phrase or section. 3. Play this section without the music. 4. Repeat this process for each section of the piece.
If you don't struggle to play without the music - you will never develop your musical memory.
After you sucessfully memorize a piece, continue to play it daily from memory. Try to memorize one tune per week.