If you're serious, and it's a British coat-of-arms, then the College of Arms is your best bet. They're not people to just muck about with as they'll charge you for any services and probably upfront. They have access to some of the best resources in the world for any such research (incl. identifying crests and coat-of-arms), but if you can access the British Library Western Manuscripts room you would be able to make use of a couple of books to identify arms yourself.

I'd stay away from most heraldic and 'ancestry' sites, unless someone can vouch for their dependability. They seem like shysters at the best of times. They're more interested in getting your cash and a good review than providing an honest service.

If you simply google your name and "crest" or "coat of arms", you'll most likely end up on a sham site selling you a fantasy crest to hang up on your wall.
If you're really looking into it, you need to know more about your family's history. Where are you from? For countries that have been under Austro-Hungarian rule for some time, Siebmacher's Wappenbücher (for the respective crown land) are a good source.