Transcribe transcribe and transcribe.
Get hip to ii-7 V7 I maj.7 or even iii vi ii V I.
Upper extensions- 9s, 11, 13s
ALWAYS ATTACK THE DOMINANT - use alt extensions (b9 #9 #11 b13) and alt scales for doms - phrygian dominant, octatonic, alt scale etc.
Listen to tons of jazz. Maybe start by focusing on mid 50s to mid 60s.
Miles, Bill Evans, Coltrane etc.