With regards to hair...I did read (somewhere...can't remember where though) that it is important to make sure that the electrodes have as much contact with the skin as possible. So you do want to try to move as much hair as you can out of the way. Along that line of thinking I suppose it could be more difficult for someone who has really thick hair to get good skin contact where as someone with NO hair would probably have the best. It was sort of a pain for me in the beginning to figure out how to move my hair out of the way for the electrode (only one is an issue with this because I don't have any problems with hair on my forehead). I guess in this situation it is a good thing that I have fairly fine, thin hair.

I also remember reading that you want to make sure you have a nice clean spot to place the electrodes...no hair products or anything should be in your hair.

Not sure if that will help at all but that's all I know about it.