I DIY as much as I can within reason. I couldn't begin to count the amount of money I've saved over the years. Plus, when it's something you've worked on, it's even easier to work on in the future because you understand it inside and out.

I don't work things I don't have the knowledge to do safely (some electrical work for example), or things I feel I don't have the knowledge to do correctly and there's risk of really bad resulting issues (I don't touch load-bearing walls for example).