how do you start your levels
 

i know with myself when am making a world i first make the water line then the trees then and so on, but some people finish one level at a time and keep going what do you do, and when making towns what sets the type of town your making,
I personaly think its the path but thats just me.

depends on what i plan to make in the level, if it's a town i start with one house and build outward, if it's a cave I just start at the tops and build down from there and adjust my walls to fit as needed when i add new curves, etc.