I think good practices are something you get into when you start to work with computers for any extended length of time. I've been fiddling with computers since 1973. The bad habits I've discarded (I hope) are

• Stupid or obscure variable names
• Who cares about indentation!
• We don't need no stinkin' backups!
• Just jump in and starting coding!
• Documentation is for wimps!

The good habits that (I hope) I've retained are

• Sensible variable names
• Proper indentation and nesting
• Use of RCS, CVS or at least saving the original before I start hacking
• Some thoughtful meditation about the problem at hand -- ideally away from the keyboard
• Documentation can save your butt -- just do it

My good habits as a C programmer for fifteen years carried over nicely when I started learning HTML in 1997 and Perl in 1998. No, HTML is not a 'programming language' (since there is no concept of variables, looping, conditionals, and so forth) but I suppose you can say you 'code' in HTML -- since there are many ways to 'encode' material in order to come up with a 'result'.