If you want to be sure where your spam emails are coming from, when you sign up for a website that asks for your email, append +website to it, like this:
rb.cubed+twistypuzzles@googlemail.com . The + and anything after is ignored when it is sent (so it'll come to my inbox) and it'll show in the header that it was sent to 'rb.cubed+twistypuzzles@googlemail.com'. Now I know if I get spam from that email, it was sent from twistypuzzles D:

Also, use alternate domains (googlemail.com instead of gmail.com) if you can. These can be filtered out of the inbox and sent straight to the trash or spam.