I'm actually serious about this -- read anything on HFT strategies online with a grain of salt, because you are the type of person HFT firms are looking to exploit. In HFT it can be very hard to know if you're the hunter or the prey.
Some strategies that involve complex positions might post small daily returns. Then, an event can come along and wipe out a month of profit, or more. It's a shark eat shark world.
Right. HFT relies on finding arbitrage opportunities, which are limited and temporary. Unless you're building AI that will adjust to other players' strategies in real-time, you're behind the game.