i realised my 3mths old baby is tending to keep twisting his body and stretches himself at this stage now, how can i encourage or teach my baby to learn how to flip successfully?

Baby’s gross motor skills all develop at different paces. So first of all, let your baby determine when he’s ready. Of course you can facilitate the process. Be sure to remove any obstacles that might interfere with his try-outs. Are tight clothes an obstacle? Is the surface preventing him from flipping sides? Etc.