I cant really explain an answer to your question properly, so ill tell you what i do. (i dont know if this is micromanaging or not)
When ive built my first town (4000BC), ill look for bonus resouces within my territory. If there are Cows, ill irrigate em + road, if wheat, ill mine (unless on flood plains) + road, Game ill put a road onto them.
By this point, if ive already improved more than 2 squares, then ill look for a Luxury Resouce inside my territory, and build a road to that.
If ive not improved 2 squares ill look for some Bonus Grassland, if none then ill probably restart the game

. If there is some, ill mine it/them + road.
I repeat this process for all of my other core towns, and then work my way back to the capital, and start improving the terrain that is being used/will be used.
I know this isn't very clear, but i hope it helps
