1. Only post photos of girls. If you happen to be a girl, self-portraits also work. Just remember this equation: more skin = more views.
SIDENOTE: If you're going to post self-portraits, ONLY post self-portraits. You don't want to give someone the option of looking at someone other than you.
2. Only post one image per day. Keep viewers wanting more, but be consistent. Fewer photos means more views per photo.
3. Use Photoshop. People often confuse Photoshop with photography skill, so use this to your advantage.
4. Collaborate. People like to see familiar faces, so shoot fellow Flickrites. Be sure to shoot high-profile Flickrites, otherwise nobody will really care.
5. Write interesting captions. Pretend flickr is your blog and make it personal. The longer the story > greater chance of someone relating to you > greater chance of someone leaving a comment.
Good luck and Happy Flickr-ing.