Add the friends you like, and block the chumps you don't.
Did you enjoy grouping with someone? Did they know right when to toss out a heal or buff? Or maybe they would mercilessly hunt down enemy archers before they started pelting you with arrows? Add them to your Friend's list and it'll be easy to team up with them in the future. Having people in your Friend's List allows you to see when they're online and makes sending them mail and inviting them to parties a breeze.
On the other hand, if someone is snatching up all the weapons they can't even use and not pulling their weight, don't be shy to add them to your Blocked Players list. It may be harsh, but when battling baddies through the halls of Curtis Castle, you need someone you can trust to have your back!