Yes I write on my hand.
I have no colour preference - I use whatever comes to hand. (you asked for that one)
Nothing is written on my hand now.
I write on my left hand as I am right handed.
I do it because I have erratic mental processes (OK I am disorganised and have a bad memory because I get side-tracked a lot) and I can and do lose pieces of paper and I have never (thus far) lost my hand. The other useful thing is people will ask what you have on your hand and why and this helps to remind you what you needed to remember.
I put notes on my hand to remind me to do something that needs done at a later time, perhaps on way home from work or at a certain (later) time.
For example, notes might read "milk bread" "pay insurance" "petrol"."ring Dr" "take tabs"
When my children were small I would also write on their hands when they went to school. Their notes would read (typically) "coat" "shoes" "homework" - all the things they were likely to forget to bring home.
**I only write on the back of my hand - I don't know why - perhaps better visibility. Actually when I think about it I have a definite aversion to writing on the palm of my hand - how odd.