How do I ask someone in an alteration shop exactly what I want?

Does anyone have any keywords that would help me explain to an alteration shop about problems with my jeans? I would like to have a little knowledge going in the alteration place to avoid confusion. Basically, I would like them to be a little tighter all around (I don't know how to measure tightness) and cut 1 and a half inch on the bottom leg. So how would I go to an alteration shop without sounding like an idiot? Thanks in advance.