Pot Limit Omaha (PLO) is one of the most fun poker variants you can play online. You make big hands far more regularly than in No Limit Hold'em, the pots grow larger and do so faster, and the less experienced PLO players make the same mistakes over and over again, leading to PLO being potentially very lucrative indeed.
Most PLO mistakes can be prevented preflop. Think of the preflop stage of PLO as building the foundations of a house. Start from a solid base and you have a platform from which to build.