I am a new player in the TW world, I have downloaded Attila, learned the basics with Sassanids (I went about 40 turns in), and I have decided I'd eventually start the ERE campaign. The unit system seems to be pretty complicated for me, so which units do I need to go for ASAP in the tech tree? I think I can deal with tactics somewhat, but the unit system is, at least for me, having less than 5 hours in the game, very complicated. Input is appreciated.