Tsen's given some good adice about the reality checks. A good idea for when to do them is whenever you get curious. The RC I use most often is holding my nose and trying to breathe. If you can still breathe in through your nose when it's plugged, you're dreaming.

I have a very active imagination, but I am also a very accepting person of things both in real life and in the dream world, leading to my unquestioning nature in dreams. I'm working on that right now, though.

If you have any other questions feel free to ask

-Amé