1. Join a flickr pool
Whether you are into HDR, dogs, or food, there is likely to be a flickr pool that has members who share your interests.

2. Know and use flickr privacy settings
Just because some people make every photo public for the world to see, you may want to actually use flickr’s awesome privacy settings so you can show some photos only to friends, and even customize who can comment on or place notes on your photos. That way you don’t have to worry about your boss seeing those incriminating New Year’s Eve photos when you call in sick on January 2nd.

3. Use the “Add to Faves” feature
On the upper left corner of all photos on flickr you will see this button. If you are too lazy or shy to write a comment, or you simply just love a friend’s photo, click that button. Your friend will get a message stating that you have added it as a favorite. Social, but passive at the same time, how great is that?

4. Get yourself some Moo Cards
Moo Cards are one of the best social tools (not to mention marketing tools) that flickr has going for it in the off-line world. Every time I give a Moo Card out to a friend who doesn’t use flickr, or who doesn’t know that these “calling” cards exist, they are in awe of it, and want to know how to get their own.

If flickr knew what was best for them, they would offer a free 10 pack of flickr branded Moo Cards to all new flickr-pro subscribers, who all would become instant evangelists of the site with their friends, hand out cards, and create their own social circles on flickr. Et voilà! Flickr becomes more social and less of a repository.