Mix up your serves to keep your opponents off balance from the very first shot. One way to mix-up your serves is to use a lob serve, which is a high, loopy serve that is high and deep in the court (and is a good alternative to a traditional straight, flat serve). A lob serve could keep your opponents deep in the court, as well as give your opponent an awkward height of contact and pace when hitting the return of serve. This will make it difficult for your opponent to hit his or her return with any pace—which means that your opponent may be likely to hit the pickleball out of bounds or give you a short return, setting you and your partner up for an aggressive third shot. Plus, you and your partner will have more time to react to the return of serve, since it will be traveling with less pace.
Bottom line: Mix in a lob serve to add variety to your serves!