One of the main reasons to transcribe something is to learn new skills...to be able to hear and play things that you previously couldn't. Get tons of JJ and Frank and Carl, and Conrad, and whomsoever else you like to listen to. Transcribe them, then learn them a couple of bars at a time, very slowly. The longer it takes you to be able to play it with the CD, chances are the more chops you will aquire in the process.
Here are some recomendations:
JJ and Stan Getz Live at the Lighthouse
--JJ's Yesterdays solo is one of the most beautiful recorded trombone solos ever, IMHO. Actually, any JJ would be good to transcribe. For starters, why not transcribe a couple of standards that you are working on learning.
Frank Rosolino Free for All
--Try his solo on Stardust. Fond Memories Of
is another good source, but don't sheat with the transcription book that's on the market!
Carl Fontana The Great Carl Fontana
or The Hanna Fontana Band
Lots of swining Carl on both.
Conrad Herwig-any. His pentatonic approach is unique in the trombone world. Difficult to do, at first, but that's how you learn, right?
Hal Crook--For some really advanced improvisation, transcribe some of Only Human
. Holy cow.
Don't sell yourself short, and don't aim low. When you hear somebody do something on the trombone you can't do, it just proves to you that it can
be done. All you have to do is figure out how