Have a look at The Grid on youtube, by Scott Kelby, especially the “blind critique” episodes.
Watch this video too https://www.youtube.com/watch?v=_3TP7JBHFmw, if only from 1:00 to 2:25, to get an idea of WHAT to share with others.
This guy may not have the best photos in the world, but his idea is rock solid: if you think you want to share a shot it with others, look at it and tag it, and CLOSE THE PROGRAM for that day. Return to it tomorrow and look at it again. Believe me, you will see things you want to change almost instantly. The thought may go through your head ‘what in blazes was I thinking?!’