1. Making 2 calls out of 1. For example: N9107U: "Janesville Tower Cessna 9107U" JVL Tower: "07U go ahead" Janesville Tower Cessna 9107U 10 west inbound landing with xray" The first call is unnecessary and clogs up the frequency.
2. Reading back everything the controller says. I have had several students read back the winds. You don't need to do that.
3. Not reading back hold short clearances. They are required and please use your N number in the read back.
I'll add more as they come in......