Remember...Class D require two way communication. If it sounds busy, gotta play your intentions like poker. Get them to repeat the call sign, and open sesame. Dont necessarily need to blurt out where you are and what you want to do...just get them to repeat your call sign. Then go ahead with the rest of it.

You- "Whatever tower, Cessna blah blah blah."

Tower- "Cessna blah blah blah, Whatever tower."

Two way established, so head inbound and give them the where you are and what you want to do. From there on, follow their instructions.