My own personal advice would be pretty much as the others have said in the order in which you create your map.

One extra piece of advice I would give is get yourself a little notebook and if you discover a way of doing something that works for you then make sure you note it down. It can be very frustrating to have to change something and then realise you can't remember how you did things after that step.

For instance, I have all the steps written down in how exactly I stroked, gblurred, blended, selected, pixel-cut etc. my landmass, coasts, forests and roads from my maps. Some of which I had to re-discover and then learned the "make copious notes" tip the hard way. :S