I would add if you go with a carrier at first, depending on the map you might want to actually build two colony frigates. The reason is one can be used to immediately poach a likely nearby asteroid using the colonize-defense platform-kill krosov tactic. However,   antimatter is a concern when it comes to colony frigates. If you have to retreat and jump to go to the other direction where your carrier killed a neutral fleet (or 2) then you might have to wait a long while to colonize those 2nd and 3rd planets (jumps + am delay to colonize). Also colonize in the direction of your enemy if you can and leave those nasty planets with big neutral fleets that are in your backyard alone until later. Oh and if you are initially going for one cap ship at the start (the usual practice) then don't be afraid to scuttle the cap ship factory. The more money you pocket early the faster you can expand your borders or build your econ.