I've always worn braces to work, coupled with trousers one size too big.........makes getting up and down scaffolding and general movability a lot easier. Also the trouser one size too big (which only really work with braces) allows you to fill your pockets with easily accessible bits and pieces - I don't like tool pouches and very rarely use them.
I wouldn't wear braces with a suit however, unless you keep a jacket on all the time - makes you look a prat imo.
Belt and braces, preferably with a detached shirt collar, if you want to look like Alf Garnett.