Really? With Theo?
Be aggressive in founding a religion and spreading it like wildfire. With Tithing (+1 gold per 4 followers) and (I forget the name?) (+2 gold per city following the religion), which only Byzantine can take as a combo, you can have loads of gold pouring in, if you get that religion pumping everywhere. A desert start is even nice for them because the +1 faith per desert tile is about the biggest faith increase you can get if you have a big swathe of it around.
If you aren't founding a religion as Theo, you're basically wasting the whole UU, and if you're not aggressive with it, you're not leveraging it that well. Byzantine has the most adaptable religion possibilities. 'Just Defenders' and/or 'Faith Healers' for religion perks can really make defending these cities a breeze.
Everything else would seem to be your general strategy, if you had really outlined what you do.
I usually pop a monument first thing while researching pottery, follow with a shrine, then straight into a settler - while taking liberty left side in social policies. Usually end up completing the built settler plus getting the free one at nearly the same time. Gets you up to 3 cities pretty quickly, which is usually the limit before other civs start "we hate your aggressive expansion" on you. If there are warmonger civs, pick more defensive locations, like on top of a hill, or on the side of a river away from them (or both!) instead of the perfect layout for resources. If YOU want to be aggressive, found your cities towards their land and save land "behind" you for later expansion. If you wanna be more defensive, settle away from them, because going near them will usually get "we covet your lands" and you can be sure an attack is incoming.
And if you really wanna mess up an attacking AI's army, drop your great general into a path they're likely to walk through - 2 hexes out from a city is great, because they'll continually walk through it and die attacking that city.