I find the key in all my emp games is the REX. You either get boxed in, or you sprawl out. In the first scenario, it is hard to get out of unless you have a weakling neighbor. In the second situation you are golden. You NEED a decent settler factory, and just try for the republic slingshot. Beyond that just make sure you are always expanding your empire through small or large wars, doesn't matter, just don't ever let your empire stagnate because you will always be out-produced on emperor, so size matters big time, and TRADE TRADE TRADE.