I don’t think too that it exists one RC which will work for everybody, but the nose RC has proven to be very efficient. We made statistics on another forum and it had very good results.
OK, so this experiment has changed. no RC is going to definately 100% work, i was just trying to find an RC that will prove more reliable. if you ask someone in a dream if you are dreaming almost always they will think (and act) as if you’re crazy. even reading text four times isn’t garaunteed to work - i once had a LD in which i spent the whole time reading text again and again and it never changed. if you have an LD, just see if there’s a pretty sure RC to do. you could even try asking your DG about an RC.
RCs don’t work for me. I try them 20 times a day IRL but not once in a dream 
In the dream I just realize I am dreaming, in a weird way!! It’s like I already know it and I’m just reminding myself…
Sort of like the looking at your hands one–
Try writing a word on your hand, then throughout the day look at it and say it to yourself and all that stuff. ^^;
Then when you’re dreaming, if you look at your hand and the word is different, or it isn’t there, you know you’re dreaming.
Might not be completely fool proof and guarenteed but its worked for some of my friends that I’ve talked to-- and I’m trying it today. ^^;
Got one important question; when you say the hand RC fails you, what excactly do you mean? Your hands didn’t look funny? Is that the whole RC? My hands (NOT number of fingers) look normal in my dreams.
I have tried a lot of RCs over time, and can sum them up like this:
Couting my fingers: have never failed me. In my dreams, I always have less or more than 5 fingers on my hand. Please note that my hands look normal apart from the number of fingers.
Block my nose and breath through it: works most of the time, but have failed on occation.
Looking several times on a clock/watch (both digital and analog): not very dependable. I can see normal times on both, and they don’t change. In addition, the time usually is what you would expect according to the time of day in the dream.
Closing one eye looking at your nose: don’t work. My nose is still there.
Flipping lightswitch: terrible. More often than not the light will turn on/off.
Reading text etc: not working.
Asking myself “how did I get here?”: usually works, but I still dislike it.
In conclution, the best RC for me is counting fingers. This is also very fast and easy to perform. And if you are in public, you don’t look stupid while doing it 
I think the best solution is a RC combo. I usually look at my hands, look at my nose (to see if it’s missing), then hold my breath. I’ve gotten used to doing everything in a swift motion, so it doesn’t look too weird and it’s easy to be done.
in answer to Moonhunter’s question:
i will look at my hands and count my fingers and i will have ten fingers. usually i already know i’m dreaming, (i just enjoy seeing how weird my hands are) so this makes me very confused. i will then re-count them, look away and count again - and they still look normal. Frankly i don’t think any RC is reliable. The best thing to do is enter the dream thinking “ok, everything around me is part of a dream”. All my dreams start out lucid, but usually i lose lucidity.