honestly it’s not a bad strategy to learn how to animate well *without* tweening first

step 1 practice with simple movements, set a goal and animate it

slap a floor down, put a character, and make him walk
then jumping

then if you want, combat things, punches and combos

watch other’s animations and see what it looks like, try to emulate it, pay attention to all the little intricacies of the movement and understand what you’re doing with each pose on each frame

also, watch tutorials like this