I read a little while ago that adding lemon juice to your hair can lighten it.
So, what do i do?
Id obviously do a strand test first, but Im sure I read something about drying the hair with a hairdryer to bring out the colour-am I right?
Also how long does it last and really is it any GOOD???

You have made me smile, when I was at school all the blond girls used to use lemon juice on their hair in the final rinse to keep hair bright and help the sun to bleach it lighter in the summer.
I used to use it on my horses tail
Brunettes always used beer, yes real beer the same way to keep it looking glossy.
And of course the redheads have always had henna.
Me? I'm glad I live in an age of pre lightening treatments that don't leave my hair like straw and conditioners that smell good and really work

the thing to understand is the chemistry of the hair especially the ph......ph of hair is around 5.5 hair dyes, bleaches , perms fall into the alkaline category the more up the ph scale.......the more damaging......to a certain extent acids such as conditioners which are slightly acidic which bring the ph right back to its original state are better than alkaline but.........further down the ph scale regarding acids...can be just as damaging as alkaline...
ph of lemon juice is 2.3 thats in the "very strong acids" category.....not very good for your hair plus you would have to use a heck of a lot for it to show any decent lightening on the hair. and plus it will have quite a damaging effect on the skin too

there endeth the chemistry lesson...pmsl