Good RC methods include:

Looking at your hands - hands often appear different in dreams
Holding your nose and trying to breathe through it - obviously, if you can, you're dreaming
Looking at text or a clock, looking away, and then looking back at it - the text may change or be replaced by strange symbols
Trying to recall the last few places you've gone - if you can only recall "going to bed" you're probably dreaming.

Those are just the ones I've got off the top of my head. You should do these throughout the day so that possibly you'll remember to in your dreams. Honestly, it's never really worked for me, but it has for a lot of people.