If you want to practice lip syncing, try looking at a phoneme chart which shows a diagram of general mouth shapes that occur when making certain sounds that then form words. You can find a ton online with a simple google search.
A good way to then test your use of these shapes(in your own drawing style of course) is to use a phrase emphasizing a lot of each sound.
e.g.
"The quick brown fox jumps over the lazy dog"
"Sibilance"(this word highlights several consonant sounds and is used in mic checks)