tristanlist: Also to prevent the labor from going negative, watch out on the following items- they draw surplus population
on that turn and if they make your labor go negative your economy gets mauled.
I won't be so badly concerned about this.
Sure, you want to watch labor availability for your first colony, but don't let it slow you down too much; if you in negative upgrade a house instead of industry, or even drop another church if early enough (but I rarely build those at all, and never bother to upgrade them above level 1 (well, I make one level 4 somewhere if I spot the Ancient Ruin to make sure it not unlock the Crusader).
Overall, if you fall short of labor, your dominant industry of that town will suffer gradual reduction of output until it not much of dominant anymore, after that all others will be cut proportionally. Sure, it not nice in your first town early on while every single thing matters badly, but in additional colonies that receive most resources by transfer initially I can't bother less. I have had 3k colonies with 8k labor demand, as long you don't have housing shortage it not tragedy, they will come eventually.
Now, some tips to save on labor.
- start with a single Fort initially. Forts require labor, and draw it before any industry do. I never recruit lesser units anyway (unless heavily pressed to do so) and it is much better to start and upgrade them to level 4 one-by-one.
- eventually you want 12-14+ docks in your main commuting cities (and at least 4-6 anywhere else), but be mindful of spamming those too early - they require a lot of labor when upgraded, and just as forts draw it before industry.
- only place War College when you are ready for it. For me it means to be able to spent upwards of 2k gold on it every turn from then onward, it barely makes any sense to have before that. (btw, I spend my first 30k on leader research for nice recruits with 40 points; before I do that I only recruit one leader next turn after upgrading my first town center to level 4)
- for me, it is more labor-effective to upgrade industry buildings not place many more low-levels. It may not be true, but I have feeling it also hurts less if (when) you fall short of labor if you have few high level buildings against having a multitude of small ones (possibly they shut down one building at a time, low ones first?).
Obviously, finished colony should have about 600~1000 more housing than labor demand to house army and offer flexibility for various recruiting.
tristanlist: Troops in town take up living space, but they are castrated robots. They don't eat and don't contribute to pop. growth.
I have seen old tips suggesting the opposite must be true, but I will agree with you on this. So, it is worth the risk to keep army near the town not in it for the few first turns while there is housing shortage.