You need Hazard Pay, which will be expensive. Free Port is also good for income and population, but will aggravate H and Church, which is not a good idea early when player is not ready to fight expeditions.
Accessibility is important. Try to colonize close to core if possible.
Cyrosleeper is nice, but even if it is in a system you can colonize, you only get a partial bonus (up to +25%, like another Free Port) unless someone produces 10 organics in the sector. It is sizable, but as not as big as people think without having Organics 10.
I prefer not to exceed 150% hazard on non-habitables (player will need at least one for fuel planet with synchrotron, and probably another for resources). Up to 200% is acceptable if there is a good reason (high resources, need big fleets from Cryoarithmetic, ideal location).
Player can personally govern one colony with +2 stability bonus, two at no penalty, three at -2 stability, and so on. Player can eat a -2 stability from three worlds no problem as long as he does not stack both Commerce and Free Port. Four starts to get painful at -4 stability, not something to do for long-term.
Personally, I prefer not to exceed two worlds, but I will go for three temporarily if I need to. Not a good idea to rule too many yourself unless you get Industrial Planning for yourself. Eventually, you will get admins with IP (human or AI cores), but unless you want an Industry capstone, you want to avoid taking IP yourself.
For human admins, stick with unskilled ones at first, then upgrade to IP ones when you need them and colonies start producing enough income to pay for their upkeep.
Most players who are into colonies eventually grind Ordos for alpha cores and stick them in everything, and do not care much about inspections or Pather cells.
Dropping commodities in colony resources means they consume it if they have a shortage AND using stockpiles is enabled (which is disabled by default). Otherwise, it just sits there doing nothing.