When I teach a junior tennis player, I insist that they learn an excellent second serve -- usually a kick or "lifting" serve. It takes them a while to master it, but it pays off in premiums for the rest of their tennis careers. It stops the dreaded scenario of missing the first serve by over hitting it, then losing on the second serve by pushing or just getting it in. When that happens, your opponent dominates it and you.
 
As I teach adults, they very often suffer from that syndrome as above. I used to think they could not learn this "kick serve," however it's just the opposite.
 
Once they learn to bring the toss low and a little back, they realize the advantage of a spin (lifting) serve. Bend from the knees and just a little from the back. It can be hit with tremendous racket speed, which in reality helps bring the ball down. It is effortless, it has great movement and players hate the high bounce.
 
I tell all of my students that all shots can be graded as slow, medium and fast. This is concerning the racket head speed. I ask all of my students to hit a medium or fast racket head speed for the first serve and only a fast racket head speed on the second serve. Once you get the hang of if you might even use it as an occasional first serve. It's great on a windy day or when you are nervous, because it has high net clearance.
 
Good luck on the courts!