How do I buy a ring from a jeweller?

I plan on proposing in about a year to my girlfriend. I don't want to spend a fortune on the ring but I want it to be nice. How do I go about buying a ring from a jeweller for the best price?<br><br><br><br>Edit: Thank you everyone for the advice. I think I'll look online first to get an idea of pricing. Then I'll go to a jeweler.