Web page construction done properly

I've been creating some web pages from scratch, which is something I haven't done in a while. They are for our new on-line donations server, which isn't live yet. I created pages for approval in Microsoft Visual Web Developer 2005 Express edition, and then doing them for real in Blackbaud's NetCommunity.

Usually with stuff like this I just do the minimum to get it done... and this time is no exception. However when I do further work I'm determined to do it properly. Properly means making sure that my (X)HTML is valid, that I plan before jumping in, that I understand why what I did works the way it does, rather than tweaking until it looks good, and other worthwhile things. On the subject of valid HTML, I ran the home page of some, er, websites that belong to a friend of mine, through the W3C validator and I'm embarrassed by the results. Fortunately I'm not responsible for our, er, my friend's web pages.