Most likely things like version control, static analysis, dynamic analysis (e.g. Valgrind), automated testing, and code review. The Joel Test[0] is a good starting place.
Actually, Joel has a lot of great blogs, not just the one on the Joel test. Browse through the titles and read any that seem interesting. He has been writing good material for many years. Of course he is not the only great blogger on the topic of software engineering, so whenever you need to google for info on a topic, click on the More... dropdown and select Blogs to find more great bloggers.