You can find lots of crazy guides telling you to separate pomegranate seeds from the pith and membrane in a bowl of water, but none of that nonsense is necessary. (I also don't find that the seeds benefit particularly from their dunk in the water.) Eating a pomegranate is easy and pretty quick in the scheme of things, once you get the hang of it. Just follow the simple directions here and you'll be eating pomegranate seeds in no time.
Look for plump, rounded pomegranates (they dry out as they're stored, and older specimens will have started to shrink a bit as the thick skin starts to close in on the seeds) that feel heavy for their size and are free of cuts, slashes, or bruises.
Pomegranates do not ripen after they're picked, and yet bruise relatively easily when ripe. This means a lot of pomegranates are picked a bit under-ripe. You are much more likely to find truly ripe, fresh pomegranates at farmers markets, co-ops that get deliveries directly from farmers, and farm stands.
Once you tire of simply popping the sweet, juicy seeds (the juicy parts of which are technically arils and not seeds, which are the slightly crunchy bits at the centers of the arils) in your mouth, check out these 10 Ways to Use Pomegranates or see How to Make Pomegranate Juice.