Here are a couple quick, easy things you can try.
1. Find any old racket with a head cover. Stick a paperback book inside the cover and practice the serve without a ball. Concentrate on getting everything right- then hit with your regular racket.
2. Find an old, heavy-ish, wood racket and, again, practice hitting the ball with good form. You will really need good form to hit well with a wooden racket- then try your regular racket.
3. Alternate between these 3 things as a king of practice to find better form, increase setregth and speed, and get the feel of hitting the optimal serve (if you do otherwise with a wooden racket- the results and feel will be very bad).