Usually, I disband all ships and cavalry that I have at the beginning of a campaign because I generally don't need them. I find myself not to be a large cavalry person anyhow and only use, at most, 4 units per stack. They cost too much to be used this early in a campaign anyhow. The Romani has a relatively good economy as far as economy goes; I believe at the beginning they're actually earning money! This is in contrast to some barbarian factions where they have at ton of money in the hole if you don't move fast or the smaller factions in the eastern part of the map.

Anyways, just try out what you can. Generally you won't find yourself being able to blitz like RTW or as fast anyhow. Some factions you may need to disband all units and wait out a couple dozen turns so you can get a good amount of cash to start conquering. I did this in my Casse and Hayasdan campaigns for example. After you conquer a couple towns, your economy will get better. In no time, you'll be building buildings in all your towns. That's one of the things I also aim to achieve. I don't want to waste any sort of time as I want my cities upgraded quick and fast. So I generally always have less than 50,000 mnai, except for this one Koinon Hellenon campaign where the money was just rolling in and I couldn't build fast enough to counteract it. The economy in EB is generally like that. First you're dead broke, then after a while, rich as hell.