his dick keeps falling out when i get on top + need riding tips

okay so i’m not exactly used to being on top, i’ve only done it a few times but i feel like im worse than i should be. i feel so awkward when i get up there, like im not moving properly and just look silly. also, his dick CONSTANTLY FALLS OUT. it’s not that it’s too small, he’s pretty average sized so clearly it’s something i’m doing. i feel terrible about it and like he’s judging me so badly, this is gonna sound dramatic but ive cried multiple times over it😭 please please someone give me tips.