Hand signals for cyclists and motorists are the same in North America. Yo won't see too many drivers using them unless they're conscientious and know their flashers aren't working. But this takes us right back to "which brake". You have to use your right hand to brake while signalling with your left. If you're a back brake dragger, you use your back brake; if your front brake is your primary brake, you use the front. Of course, you should have your braking and signalling done before you actually start to turn. Both inexperienced drivers and cyclists get that part screwed up.