I'd agree with all the 'nothing' and 'lots of small things' above but I'd also like to add one more to the mix; something that you caused ;)

I learned years ago to just assume I caused all the problems. It saves time.

Usually I didn't, but when you approach it like "What did I break, and how can I fix it?" it is much more useful than taking time to assign blame to others. Also it looks better to managers.

If it is something particularly nasty you can check version control when done, but most of the time isn't worth it. I often respond to queries about broken systems with "I wonder how I broke that..." because in some code bases a change in one place really can cause unexpected behavior in the most bizarre places. Being someone who submits a lot of changes affecting core functionality also means you are likely to break other people's stuff. A GPE working on the fringes usually only breaks his own stuff.

One tech lead I worked with had an interesting viewpoint. As developers grow in skill, experience, and domain, the bugs they cause should be even bigger, more powerful, and harder to fix. A good developer will constantly challenge himself. Bugs usually require more brainpower to find and fix than to write, and if some tricky bug took the full brainpower of a senior engineer to construct you know it will be nasty to fix. A junior engineer who breaks the build with a missing semicolon is fine. When a senior engineer breaks the build you can tell they are doing their job well when the breakage is a subtle change that takes the entire team out for three days and five people hunting through the code can't find the bug even after isolating the specific change that broke it.