Coins are awkward in this game, as they're always placed just out of reach, somewhere just a little too awkward to reach with normal gameplay, unless you're like, amazing, I guess. But they're well worth adding up to your score, so try and go for them. Of course, remember holding the screen will make you jump farther, and your double jump will save you from many awkward deaths. Though, since the checkpoints in the game are quite generous, if you're not going for high scores and are instead coin hoarding, it might be worth a suicidal jump.