I do post on flickr, because I have no time to post in many galleries, and flickr is simply pretty fast and hassle free.
I find it is a bit of a maze filled mainly with people who machine gun their digital photos without much selection criteria, but there are some valuable groups, among them the rangefinder forum, m mount, and decisive moment - esp the decisive moment classic pool, that contains only the selected photos is pretty good.
I try to look at other people photos and learn from them, when I come across something I like, I put it among my favs. This sometimes causes reciprocal interest, and this way you grow your pool of contacts, who become your restricted flickr inside flickr.
If someone puts me among his contacts, I try to look at his/her photos, and I normally reciprocate, unless the photos are a pile of digi-high-speed-machine-gun-snaps of their cat and family.
Overall, I find flickr is a place which gives you reasonable convenience and a possibility to create your own circle of interesting photo contacts where to improve your skills. My gallery link below.