On larger maps I usually capture only about 3 to 4 other planets of 9+ PQ, making one of them an economy planet.

This way I give myself time to build up my initial infrastructure, while the AIs are busy throwing their money into building colony ships and taxing the heck out of there own economies, I'm busy researching all of the lovely economy techs and the weapon techs - specifically planetary invasion.

Generally at the start of a game I put my tax at about 40% and my spending slider at 100%, the moment I need to drop my spending slider to 70% ish to be in the green is when I stop expanding, then throw money at the lab techs and those damn builders that always seem to be on a coffee break.

Through this method I'm usually on a much better footing than the AIs when they've finished their colony rush on pretty much all of the important aspects of the game, and if there are no more planets to colonise, you can start to take a planet or two from the minor races or even wage a half decent war with the major races because the AI really does take their time with researching planetary invasion (One game I was able to completely wipe out the Dregien using about handful of fighters with mass drivers and afew transports in about 40 turns or so).

In a nut shell, Develop your core systems before expanding again, you'll leave yourself with a lot of breathing room should something arise, and remember that one half developed planet is worth more than 3 undeveloped planets in the long run.

Also worth noting a generally build 3 factories on new worlds to aid their developement.

This will help too: https://forums.galciv2.com/?forumid=347&aid=169923#1390745

A lot depends on your game preferences. I tend to play a peaceful game that often ends in a culture victory. To succerssfully do this I have to load up on economy ability and play the Federalist party. Playing as the Terrans (or an economically gifted race like the Korx) I can usually make it through the tight period without letting the AI get ahead of me in real estate. You have to be careful with improvements. Most of my outer planets only have one factory and a star port until the money starts flowing later in the game

If you like the war game it doesn't matter if you have a huge number of colonies. As long as you have 5-6 that are well developed and with decent PQ. Play it as Domage suggests and you will be fine. Most of your real estate will come from conquest.

Honestly, one of the biggest things for you to remember in order to dodge the tax crash is that population on your cash planets is more important than having a lot of them. A planet with six economic structures and 0.05b people is still going to be in the red. Don't be afraid to use extra colony ships to ferry population to your economic worlds if you don't make your home planet into one like I do - population needs to be funneled to those worlds first and foremost to dodge the tax crash.

Another thing is that running for a while in high morale / low production to get your tax planet populations up early will help you out in the long run.

The way i kick start my economy is to only build one factory and three economy buildings on any planet i colonize until the population reaches 6bil, as at that stage the population can support further advances. It also gives you a positive cash flow usually before you run out of credits.

However this strategy may not work in TA as you get a lot less money to start and as i have yet not played too many TA games i am not sure yet.

Oh and on a side note i usually, as others have done, use a spare colony ship to move colonists to a really juicy planet if i find one, such as a PQ26 (always turned into my economy center).

I am not exactly sure but I thought once you upgrade your planet's infratructure the planet tax goes away? I am going to verify this myself once I can get Stardock working. Let me know that is the case, I am sure more avid SINS players have the answer.