RobinHood is a great app regardless of your budget. If you have any specific questions I am happy to help.

They have some useful features that you can opt-in to and are developing new ones. For instance, they're testing out RobinHood Gold where you can get $2,000 on margin for $9.99 month, instant access to funds (don't have to wait for trades or transfers to clear), and day-trader protection (won't allow you to do more than 2 day trades in 5 trading days).

I also use e-trade for OTC and Pinkies, though many also recommend TD-Ameritrade for their L2 and charting features.