Here's a good independent evaluation of insect repellents.  There are many bogus reports and testimonials about what works to keep mosquitoes away--but get the facts!  Citronella and "Skin So Soft" have all sorts of unsubstantiated claims, but anything works in town where there are essentially no mosquitoes.  Even water seems to work until it dries up!

What insect repellent do I use?  NONE.  None whatsoever!  That's right, and I haven't used any in over twelve years!  But think about it.  I'm out hiking almost every day, from early May until mid September.  Whatever organic compounds we put on the outside of our body get absorbed through our skin.  If I used an insect repellent every day, I'd take in so much of the toxin I'd be dead or crazy by the end of the summer.

No, it's not that mosquitoes don't like me.  On the contrary, I'm probably one of their favorite bloody targets.  But they rarely get a taste of me, even when they're really thick.  And I carry only a headnet as extra defense against them.  Get one that's black in color.  No, not green, not white, not even clear!  BLACK.  Why?  It doesn't reflect as well in sunlight, so is much easier to see through than other colors.