I've been using flickr for a little while now and it's become apparent that while easy to use it is somewhat limited as a service.
Flickr is a great way to share your photos and find great photos easily. It has a clean layout and if you pay the $2 a month fee then you get unlimited storage.
On the other hand there are some major things wrong with flickr.
Black and White
The biggest problem is it's design. Flickr always shows every photo against a white background. Sadly most photos look better against a black backdrop, and this can have a bigger effect on your shots then you might think.
Take this shot and it's displayed on black version. You should immediatly notice the diference. The reason for this is a little odd. The human eye actually has no default value for white. When we look at a scene we immediatly take the brightest value we can see as white. What this means is that photos on flickr that have areas that appear white on a black background look less bright and slightly off white against flickr's white backdrop.
Stats on flickr cost money. Ostensibly it's what you pay for when you spend money to make your account PRO. Sadly stats are severely limited. The main problem is a lack of options. You can't really compare shot stats, or try to understand what you did to get a photo seen more widely. THe graph flickr does provide you only goes back a month but the biggest problem is that the stats don't give you any depth; You can't tell how long someone looked at your shot and flickr has no built in system to let people rate your shots.
Groups - Too many, not fit for purpose
Groups on flickr are a great idea. With them you can collect together photos on any subject, style or quality. However flickr hasn't adapted to what groups are most comonly used for: competitions.
On flickr we generally post to groups to get our photos seen by a wide group of people. The easiest way is to post in a group where the rules of the group insure people look at your photo before they post theirs. However competitive groups are a mish mash of moderating and silly award images and despit having been around for years flickr hasn't made an effor tto improve them.
The addition of facilities to give group awards through flickr would majorly improve the service. As would the addition of a photo rating system.
The numbers game
If you do get into flickr you will probably be sucked into the numbers game. As with any website or social network we all tend to get slightly obsessed with how many people see our efforts and contributions.
On flickr this takes the form of individual views, comments, favourites and the holy grail, intrestingness.
Hits on flickr aren't that dificult to get, provided you are willing to put the spade work in. Hits are basically decided by the quality of the photo (actually not as important as how good it looks small) and how much you promote it. The easiet way to get hits is to post lots of photos into lots of diferent groups every day.
When posting into groups your shot needs to look good in a very small format. What this boils down to is that there has to be high general contrast (i.e both bright and dark areas), there has to be large details as opposed to small, the colours should be warm and vibrant and the shot should preferably be easily discernible at a small scale.
I generally post shots to about 20 groups a day and on good days get about 500 hits as a result.
Comments are received en masse in a similar way to hits. If you want useful constructive comments then you're best to post in groups where part of the rules is that you must comment and rate other photos. These groups give you useful feedback about your photos. Be warned however, not everyone on flickr knows what they're talking about and people will present themselves as experts in comments by using technical terms (Depth of field, exposure, selective contrast) when in fact they themselves are not great photographers. When in doubt check them out.
Favourites are much much harder to get. Really this boils down to contacts and the quality of your work. I have a simple method of boosting contacts and one that is beneficial to all. I add as a contact anyone on flickr who adds me first and anyone who has a shot I deem worthy of a favourite. Over a short time I have accumulated around 500 contacts who will see my photos on their contacts page and, if they like them, will give them favourites. In return I regularly check my contacts page and comment and favourite shots I like.
Intrestingness is the holy grail of flickr. We all like to get our shots into the top 500. Sadly intrestingess is hard to achive. Even your best shots won't make the list on a good day. The real way to make the list is to have loads and loads of contacts and then don't promote your photos at all intrestingness is about the ratio of favourites to views, so the fewer people who see a shot but the more who favourite it the better. This can seem a little counter-intuitive but it makes sense if you assume that the best shots don't need to be shouted about, news about them will spread no matter what.
Any and all questions in the comments