Try walnut. I'm trying some *soft* maple after cutting my teeth on, and getting pretty confident with walnut. Maple is proving to be bitchy. My board looks like crap. I'd imagine hard maple would just exacerbate all the problems I've been having, so the wood could definitely be your trouble. Especially if you have any board edges in a flamey area, which are proving effing near impossible to do anything with.
Poplar is too easy for good practice. You can get away with sloppy technique (like stripping off a perfectly formed 1/32" thick shaving with every pass) that just ain't gonna work on a real hardwood.
Save the maple for another day, my friend.