I dont know if this has been tried before, but i found avery easy reality check, and a foolproof one!
Jump!
JUMP!

Jumping in the real world will always be the same. Period.
Jumping in the dream world will most definitely end in two possible ways: Abnormal jump (enhanced height, abnormal feeling, etc) or flying. any of which is a pretty obvious sign of "hey dude, ur dreaming"

so

if you jump during the day alot, Rchecking, jumping will hopefully transfer oitself into your dreams, and voila! LD!
pretty easy to perform , obvious as a naked man in a church and, somehow, jumping in the dreamworld is pretty common, if you also jump during the day

As i said before, i dont know if this has been tried before so dont start calling me palgiary!

peace

AND DAMN THOSE THIEFS WHO BROKE INTO MY HOUSE AND STOLE MY COMPUTER! DAMN THEM!