it really depends on what you like. there are some people who just want to have as much silver/gold as possible, and there are people who collect rare coins that carry more value than just the precious metals. some people try to get every year and mint mark of certain types of coins. honestly the sky is the limit when it comes to coin collecting.
i like to collect old morgan dollars and silver eagles personally. something about the way the big silver looks really gets the ol' ticker pumpin