Lip singing sounds and look easy but doing it well enough that convinces the viewer that it is really you takes some extra effort. Some famous singers have been caught performing liver performances but only lip singing their music. All it takes is one slip of the lip and you lose faith from the viewer.
Learn various techniques and tips for improving you lip singing and check out the examples.
Enunciation is crucial, maybe the most important aspect in order to sell the lip singing to the viewer. It is all about over articulating the words with your lips. Watch the first 30 seconds of the video to see an example.
Search the Internet if you need ideas and to see some good & appropriate examples to get ideas. "ironbot3k lip sync" sometimes has good examples.