Don't expect too much. I've noticed, at least for me, its usually hit or miss and takes a few tries. I have to have 8ish hrs of sleep and even then about 90% of the time I realize I'm in a dream but the dream continues on - its as if I refuse to control my dreams and instead just try to live within them.
I receive a feeling that somethings wrong, mid-dream - for instance I'll think to myself why the fuck am I doing xyz action, or why is my watch on the wrong hand, why am I wearing these clothes I hate, or why isn't the clock moving? - at this point I'll realize it's a dream because its something I would normally not do. In one notable dream I noticed I slid down stairs like goo or a more liquid silly putty - at this moment I realized I was in a dream, but rather than doing something cool I told everyone within my dream that I knew I was dreaming and continued sliding down the stairs like goo.