How do you make sure you’re in the right poses?

Marie Laure U.
Be sure to take classes and workshops every now and then, so an experienced teacher can correct your poses. Also, use a mirror at home to check your alignment. Namasté!
Ayan Z.
For yoga, try to bring attention to the parts of your body that feel strange or good or uncomfortable, then make small adjustments to explore how it affects your body and balance.
Treat your spine as though it is a string which runs through your body and gets pulled in different directions.
An alternative is to get someone else to check your alignment.