Early on the greatest enemy of your growing economy is maintenance. Every factory or lab that you build, even the basic colony tile that exists after colonisation, cost money just being there. You can raise taxes to pay for this maintenance, but early on you want to grow your population by giving them tax breaks so their approval stays green. When populations on your colonies have maxed out, then you get no real benefit from low taxes, so raise them as high as you can go without losing population from low approval.
As you acquire new colonies you may need to lower taxes to get those to grow. If you've built up a lot of funds from high taxes, you can afford to do this (and run at a loss) for a while. Or you can provide entertainment by building those kind of buildings and by mining morale (yellow) resources.
But in the meantime, build up just a few planets with only the infrastructure you need to progress. Dedicate some worlds to producing just money, by placing economic buildings.
The advantage to rebounding from the expense colony rush early is that you can afford to buy planets from other empires sooner, when the populations have barely started to grow. And of course you can flip them with culture or invade them later on. So don't worry about not snagging everything in sight, but be concerned about how you're going to develop the tiles you do have.