While using reddit won't necessarily guarantee any real-life friendships, you can identify "friends" whose submissions you want to follow.

Once they've been "friended", their usernames will appear highlighted and a collection of all your friends' submissions can be viewed at friends.reddit.

To make someone your "friend", you'll just need to click on their username to view their profile. On the right sidebar, you'll find a list of links, one of which is add to friends. Unless he/she is already your friend, in which case you'll see remove from friends.

Now go forth and make friends.