Most DIY stuff around the house you can do. These ones to look out for are the following:
Plumbing
Electrical
Load bearing walls
All of these have extreme consequences if something were to go wrong. Plumbing can damage almost everything in your home. Electrical can stop your heart if you mess with the wrong wire or forget to turn the power off. Load bearing walls can bring your house down on itself.
Me personally would not want to deal with any of these issues. This is a perfect time to call in a professional.
load bearing walls always require a professional.