[Sparrow]

If you know in which way the price will go in a single stock with a high probability, the way to make the most is of course with high leverage.
Options are great for that, also limiting your loss.
Another thing you could look at are CFDs, the problem with them though is that most CFD brokers are bucket shops and not playing fair. And even if you find a good broker, you still might make more money with options.