Stepheno
I really think basic CSS creation needs to be covered
before the first line of code.
Another thing, even before Launching Sigil: Planning

Remember the 6 P's
Time after time, I see folk trying to
back into what they wanted. It is so much easier to set (and use) a Basic 'house' CSS, then all the rest of the CSS/code worry is reserved for those
special cases.
Plan
Collect (import: images,fonts, the house CSS, house standard boilerplate, 'the Text')
Start applying the markup