Several things I do or don't do:
I have some specialized "expertise" in some areas, such as MySQL in Ubuntu (just one random example). Every now and then I do a search on the site when I feel like diving into MySQL again. Using Google gives me way more relevant search results.
I don't use tags because of the enormous amounts of noise. I feel that they don't work very well on Ask Ubuntu. See for example Can we please disambiguate or discourage the 'mobile' tag?
The "My Tags" page as Jorge proposed doesn't work for me. In theory this should work - but really, not for me, for several reasons. Lots of them are quite old (> 3 months), tagged erroneously, been-there-discarded-that (still popping up) and worst: gone because of just one upvoted nonsense answer.
"Scanning" - Just scanning the plain active list, opening 10+ could-be-interesting-questions in tabs in the background, scrolling quickly and watching for either "easy mistakes" I can easily answer, "interesting" within 3 seconds well written questions, "less than perfect answers to questions" such as Does 12.04 LXDE have LTS?Does 12.04 LXDE have LTS? and Can Ubuntu Server 10.04.4 LTS be upgraded to NON-LTS?Can Ubuntu Server 10.04.4 LTS be upgraded to NON-LTS? were. With already one answer with upvotes these were not showing up, yet interesting to answer.