If you find your serves come back too fast, take away some speed from it and use spin instead or placement. If they come back easily, it means your placement isn't good enough. My guess being that you rely too much on your serve speed and become panicked when it comes back. However, you should see the weak return as a chance.
If you really have a good serve, it's also time to do some drills. For example, you could train how to serve a slice out wide and finish in the open court. Even it it comes back, you're most likely in the driver seat for the rest of the rally. Use your serve as a setup shot for a strategy you thought of before you served.