To refresh your memory, here's our initial work-flow chart from Chapter 3?
I was insistent that your work flow should pretty much be the following: edit -> check it -> then go back and edit some more. The main purpose of visually checking your template in FireFox after adding each piece of markup or code is, of course, to see if it looks OK. If it doesn't, then immediately debug that piece of code. Running a validation check as you work doubly ensures you're on the right track.
So, your work flow really ends up looking something more like the following:
You want to work with nice, small pieces or "chunks" of markup and ...