Ok, now, you may end up being vey good at sight reading, but setting yourself the goals of not having a problem with it within a ear or two may not be realistic, or possible. Goals should be long term, not like "I want to master the neo-classical style in the next year". So, otherwise... Listen to jazz music lots and lots and lots (did I say lots). Can you play as well as those guys? Kepp practising. Theory is very important, especially in improvising off chord changes. Phrasing is essential. How good is yours?