example game map, tick 7.

In this instance, I am Centre of the map in green, I'm heading nth & invading that player.
As I expanded, I built the 2nd fort that you now see me sending forces into battle from, my starting fort is the one far sth. :)
I was also going to fight the fellow to the Nth east but he asked for peace which I granted.
I also have another fort about to appear in the nth west, this will double as a farm fort with my neighbour to the west & attack base to supply nth battle front.
I expanded in other directions, grabbed what I could but didn't waste T on forts & structures as I had made peace with those players.

Plz Note: This is an example only, no 2 games are ever the same but there are some basic expansion principles you need to grasp to do well, & good start doesn't always mean your the biggest player on the map ;)

As a general rule, Forts should be built no closer than three regions from each other, So you should be able to count to the third region from your Home and build a Fort there, however, There are always exceptions to this guideline (very active fronts, Fury Farms, etc)
Placing Forts too close together on a regular basis not only wastes Treasure, it will actually slow your expansion by "wasting" Treasure on extra Forts that could have been spent on Lessers, Temples, or Fury Farms, so build wisely, and keep growing!

In the early stages of your expansion, theres no real need to Take every region, sometimes, you can bypass a region or two in an effort to extend your initial front as far as possible, picking up these regions with a 2nd or even 3rd wave of troops.
Forest regions are the ideal regions to skip as they only bring in 2T per tick, other considerations are regions with 1, 2 or even 0 natives in them, send only enough to take the region & put the rest with a larger group that bypasses it.
yet another option is to set predefined borders with you Nap partners & send a large force toward your enemies while sending smaller groups to pick up these "safe" regions at your leisure.