Ok, now when abouts should I do that? Like, at first, how many planets should I attempt to colonize?
I like to colonize as many planets as I can in the early game. I skip the low class ones (5 or lower) though. If they're inside your area of influence, they'll eventually flip to your side anyway.
On the small maps that I play on suicidal, I normally get two or three planets besides my homeword and then the colony rush is over. Sometimes I only get one extra. It's important to remember to land your original colony ship on your homeworld first to pick up the full 500 colonists. That way, your new colony can grow faster. Also, build your own colony ships with extra engines and fewer life support (to make room for the engines).
I keep an extra colony ship around after the colony rush is over to pick up people from my homeworld and distribute them out to the new colonies. That keeps morale even and all planets grow faster. My population is usually at or near #1 soon after the colony rush, even when I have fewer planets than the AI players.
I rush buy the first two or three factories on my homeworld and build two factories and a starport on each new colony. The new colonies are then topped up with economic buildings and my homeworld goes all factories and a manufacturing capital. I set my homeworld's focus on research and set my economic sliders to 8 or 10% Military, 0 research and the rest Social. This is a modified version of the "All Factory" strategy. (If my homeworld has a good bonus for research, I go all Labs, but we won't go there for now).
I don't use focus on the new colonies until at least one factory is built. Then, I focus on research or social, depending on what I'm trying to build. (Usually research unless there's a reason to do otherwise.)
I rush buy as many colony ships as I can before my money gives out. Tech trading will top that back up, but I'm also prepared to decrease my spending slider when I need to.
Taxes are set to allow for 100% morale until I can't maintain that level. I then lower it so my lowest planet morale is 50%.
That should get you started and well on your way to victory.
@neilo and MarshallONeil - I said my goodbyes at the HCH and moved my main character over to here. I'll leave my secondary one here too, but it'll be dormant for now.
May the evirul be with you!