I thoroughly advocate starting with an existing template :) However, one thing that's particular difficult with LaTeX is finding up-to-date information on the "current" way to do things rather than the "old" way to do things. When I taught a LaTeX course recently, I focused only on more modern things - beamer, TikZ, listings, bclogo, datatool and so on. I had to read a lot of mailing lists, blogs, community sites etc. to find these things out. I'm thinking of doing an online version of the whole course with a decent running example, once I get an idea of how to make an example that has interesting content and also gets across all the things I want to include...