Here at CAtennis.com we are huge proponents of developing a good serve. For generation, the serve has been regarded as the most important stroke in tennis yet very few players do what's necessary in order to get beyond the mere "get the ball back in play" level.
One of the least discussed effects of having a poor serve, however, is the fact that a bad server must be a great mover. Although serving and movement are not mutually exclusive - see, for example, Federer or Sampras - developing a good movement is even more important when a player is deficient in the serving concept. If your serve is less than what's necessary to be effective for your level, not only will you invest a lot of energy in trying to hold serve but you will have less reserves at your disposal to marshall toward breaking the opponent's serve - in other words, when it comes to breaking the opponent you may be mentally and physically exhausted. A decent returner will be able to utilize your mediocre serve against you. S/he will use your pace and be able to generate more angles than if you were able to put your opponent with a powerful, well placed serve. As a result, if you don't like to practice your serve - or cannot do so because of an upper body injury - you better be fast; real fast. In this regard, pay special attention to speed drill that are combined with the serve.
Here are some suggestions for practicing serve-specific footwork:
1. Start every spider sprint drill with a serve.
2. Hit a serve and immediately reply to a hand-tossed ball by your coach. At first the toss can be short but, as you progress, the feed can be more and more aggressive (into your feet).
3. Hit a serve and respond to a hand-fed drill by getting in a low, lunge position (that is, little footwork; just get down and half-volley the ball back).
4. Hit a SLOW serve that the coach will volley out of the air (or half-volley off the bounce). The quick response will force you to cover the court immediately.
5. Perform combination drills of the drill above. In addition, remember to practice serves when you are exhausted in order to build up your stamina and strength.
Lastly, when you go into the match remember that you're either the eagle (death from above) or the rabbit (runner). Even if you're a big server but are facing a deadly returner, put aside pride and remember to move like your life depends on it...because if you want to play pro, it more or less does.