One High Command will stop pirate problems at the bottom of the meter for a three to four planet system. After that, keep your Pather interest low to avoid stability and accessibility problems until you can mitigate them. After your colonies have grown a bit (without any items or AI cores) and you can take the -2 stability/-20% access hit, get your Mining/Refining/Heavy Industry threesome planet set up with a nanoforge, a fuel industry with synchrotron, fix your fleet composition, and go loot the sector to the bedrock for shiny things while your threat hovers at "increased security precautions." Farm up a bunch of Alpha AI cores too. After that, make sure you've got lots of +stability modifiers, Alphas on governorship and Megaports, splash the items out, and go absolutely nutso with colonies and heavy industry. If you have enough money to continuously build a colony up from scratch, then you can make new ones all you like and they'll get up to speed after enough buildings are in place.
The only really big thing is to not get yourself more stability and access penalty than you can afford. This is the noob trap. The top of the threat meter is a pirate raid or active Pather cell attack, and frankly those don't matter if you've got your act together. You just don't want to be lingering in -3/-4 because that'll really hurt early colonies. The pirates because pirate raids were never the problem with pirate bases in the previous patch (the raids are anemic), and the Path because active Pather cells are a solvable problem.
