Typically it's about 1 part cement to 3 parts sand, although if I remember the mix does vary slightly for the first coat. I had some good articles from the net that I've mislaid just now - I'll try to hunt them out for you. You use about three coats, leaving 24hours in between each one. The first coat you make pretty sloppy and paint it on with a brush. (about the consistency of emulsion paint) This really justs acts as a key for the coats that follow. The other two you make much thicker and apply by hand. (or by rubber glove I should say, unless you want to lose a few layers of skin !).
When are you thinking of doing this ? - I haven't got around to writing up my project yet and sorting out the pictures I took, but I should get it done over the next week or so.
