Sooner or later I always know I'm dreaming because of a logical inconsistency. I'm very nitpicky about the internal consistency of a fictional world, so when I see two things that logically cannot both be present regardless of the scenario, my brain goes into conspiracy uncover mode and I usually wake up within 20 seconds. When a situation in my sleep changes and I start to dream a lot, I end up realizing and forcibly ending the dreams over and over again. I'm pretty sure my low rate of dreaming is related to my brain just being fed up with even trying.
Recently I realized I was dreaming and my first instinct was to wake up (probably because I'm prone to nightmares and in general growing up if I ever realized I was dreaming I wanted out now), so I psyched myself up to raise my heart rate - I'd never tried this before but it seemed like a good idea at the time since the body tends to be sympathetic to things like that. I woke up in my bed safe and sound after a few seconds.
... Then I woke up again. I got incepted and the elevated heart rate forced me to wake up again even though I had stopped trying to wake up.
I'm pretty sure inceptions are just top-level dreams, then your dream changes gears to a brand new dream when you're just waking up. It would be like changing channels, or even changing channels away and then back. I don't think the mind has the capacity for nested dreaming. It's still fun to say though... "incepted"
Also sometimes I have the same dream with minor variations repeatedly in one night. Sometimes I have the same dream 5 or 6 times in the same night with small differences each time, like some kind of bizzarre time loop.