Jack, the left hand plays a huge role in the serve and can help with everything. Make sure and pay note to it. As for racquet drop, it takes some time to get that feel. I used to rush my motion and not drop my racquet deep enough because I could get away with it, but tossing higher helped. Also puling my left hand into the middle of my chest got my shoulders to cartwheel properly every time, and also gave me a deeper drop.
An easy drill you can do in your house is to serve, but stop before you swing up. Look at your buttcap and adjust it so it is pointing up in the air. Look at your left hand and make sure you are pulling it into your body to initiate the drop and the swing to contact. Get the feel for that and then work it in when you practice your serve.