A Sister in Law want to start up a beauty shop, hair dresser etc. As if there are not enough around already!! to add to the many motorbike repair shops and coffee shops, anyway, is there any law that says she or a staff NEEDS a certificate in beauty or hairdressing? SIL says no, but she is clue less on things like this.

We are involved as wifie would be partner, read the backer. It would be good for wifie as well, get her out of the house & busy

Found a good shop for rent which is very cheap. I just demand that everything is proper and above board.

Any experience in this?

You don't need any certificates or licenses to open a salon. However if they don't have any training or experience there is nothing to set them apart from the many other salons opened by people with no training and you are doomed to lose your money.

Contrary to popular belief on Thai Visa a salon can be a nice little earner, if you and your staff know what you are doing and get the right location.