Most Bungie faves are chosen from the community. If you post an epic...and I mean EPIC pic and make a thread about it, you've got a chance to get in. A few tips to help boost your chances:
1) Don't beg. Don't post anywhere in your pic "BUNGIE FAV PLZ".
2) Don't bump. Even if your picture gets fairly low on the B-net lists, if you bump your picture up you've got a better chance of getting banhammered than getting on bungie faves.
3) Give your picture a name and a description, and in both of those as well as your post, write with real words and in complete sentences. What do I mean by that? Don't do this: "how do u do that pls help me". Also, sentence structure and punctuation are your friends. Periods are good.
Now, keep in mind that this is not a guaranteed method to getting of getting into the faves. You also need a good pic, you need people to catch on to your picture, comment on it and rate it, and then it needs to catch the eye of one of the bungie staff, who peruse the boards frequently looking for those hot topics. So just remember the golden rule: "Ask and you shall NOT receive".