Wherever possible, colonise with the full half-billion. A trade centre should be second or third in the build queue. This will very quickly get your revenue up.

I put at least a 1 farm, 1 entertainment and market on every planet above class 7. Also in the begining of the game when colonizing I pretty much put my taxes at 0 to get a 100% approval so my guys can mate quickly. So basically every planet I get has the potential to have around 11B people and that gives me more then enough money to eventually go up to 100% production. You do have to go 1 or 2 turns with 20-30% production when you start raising taxes but as long as the approval is around %80 you will start getting more income from taxes.

Human sucks, you get no free bonuses and have no stellar cartography.

Shut yo mouth, traitor, human is worth playing with just because you get to play as humans. It feels good to beat a tough AI when you're human since you start with almost no techs.

Plasma4 A2, Laser3 ECM1, Construct-warp, Colony-hyper2, etc. Not too creative, but quick and easy.

1) Keep your morale high, at 100% at least for the beggining. You start with minimal population and minimal economic bonuses, no matter what your tax rate is you are going to get minimal cash from your people. You are better off having your people create more people, rather then cash. Once you have some economic buildings up and some more population (or you go broke and have to) then raise taxes to get some money.

2) On any map where you expect to colonize more than 3 or 4 planets dont buy the colony ships, buy the factories on your homeworld to get colony ships going.

3) Tweak the production sliders so you don't waste a full turns worth of production on something that is almost done. Be carefull however, social project turns to completion is buggy and may need more turns to complete than it shows. I focus on my homeworld, once it is done with its factories and an entertainment network (E network allows me to crank the taxes up to 20 some percent, slowing my cash loss while maintaining max pop growth) I shut off social spening, reduce military spending to exactly what I need to make a colony ship every other turn, and put the rest into researching or savings or whatever (and if you focus social on all your new worlds you get some social spending on them anyway).

4) Probably most important: Redesign a new colony ship! Take off the second colony module, and stick on engines and any support you may need based on map size and density. Try and play a race with Ion Engines (I know Drath have them and custom can get them, also Yor have plenty of engine space on theirs).

Experiment with full/almost empty colony ships, rushing more colony ships out or diverting their slider production to improvements or tech or survey ships.

Also in the begining of the game when colonizing I pretty much put my taxes at 0 to get a 100% approval so my guys can mate quickly.

Ha ha, your empire's GAY ha ha! Just kidding.

Human sucks, you get no free bonuses and have no stellar cartography.

U r right I play a human every second, of every hour of every day and I NEVER got any free bonuses or a map to life. WTF?

      

For the farther planets i build ships with no colony module and all engines, I then upgrade that ship to one with a colony module (and nothing else) and take the planet with 1 person. You must be extremely aggressive in the beginning if you want to win harder game levels. And I do what others mentioned about taxes low enough so morale is 100% and then I micro manage my economics in the beginning to use up every penny i have. You want to have stock markets earlier then later not just for the money, but the added morale bonus you get. I personally like to get trading up early as possible also to improve diplomacy and for additional income early in the game. Once you get big trade becomes less and less important.