You can get a dash cam that will give you safety camera alerts, like the Mio C330 (review here: kit.honestjohn.co.uk/reviews/review-mio-mivue-c330.../). There are also a few dedicated safety camera alert devices, like the Cheetah C550. Or you could opt for a smartphone app, like TomTom’s Speed Cameras app. However, while it's easy to stray over the limit - especially in unfamiliar areas - the best way to prevent being caught out is to be aware of speed limits and stick to them.