Go watch this film. That's the best advice I can give you.
Rockstar is a peerless film, rich in texture and detail, and enriched by complex and well-realized emotions. It has an almost-perfect lead, and a literally and utterly flawless musician scoring it.
That said, it is a film which has many weaknesses - in the acting, the writing, and the point it tries to make - but warts and all, it is a film that is hard not to recommend.
It is easy to get into the defects - the music is informed by the locations, but never the emotions of the lead, never get....