Dont - woman should not attempt to shake hands with a Mauritanian man, unless he extends his hand first, in particular the older generation are quite sticky about this. Woman should also try to have a male companion when travelling or hanging out at the beach.
Do - bargain, dont accept the first price offerred. Also Mauritanians have different prices for the same goods, depending on your nationality! If you think the item is too expensive tell them you are not American! They are a wonderfull warm people, do communicate and smile.