When I was the only guy in my team writing code, I found it helpful to put a bit of processes - like having a threshold of test coverage, and running some kind of analysis (flake-8, for example) on my codebase. Another thing I did was letting one of my friends look at a random piece of code in my codebase. He would suggest changes, but what helped more was that I wrote code more consciously than I would if I did it all alone.