Read up about stoicism, nihilism, cynicism. Also esoteric texts are interesting too. Also seeking out esoteric knowledge that isn't well disseminated is highly interesting to me. Nothing like the rush of an esoteric book!
Stoicism is, to my knowledge, the only branch of philosophy that feels useful to me. It's like an insurance policy -- care about doing right, and act accordingly, and you will be content (if not comfortable) no matter what happens. The world really would be a much better place if it had more stoics.