A great way to get this input is through a critique group. A critique group is a gathering of individuals who have agreed to share work with each other and get honest input on it based on their experiences, taste and talent.
I have been members of many and have enjoyed some and loathed others. The problem can emerge when you are dealing with other artists that you may not truly consider your peers. Most crit groups I have joined were with strangers. I wasn't familiar with them, there artwork or there temperament and they weren't familiar with mine. This can make it difficult to want to share your artwork and open yourself up to critical input. Many of us have very personal ties to our artwork and having someone tear it apart is like having someone criticize our children or a dear friend. (This is something we have to get over as professionals, but I acknowledge that many of us are still developing that thicker skin.)
I've cultivated a number of relationships with fellow artists through social networks. Many I have to come to admire and respect as my peers and fellow professionals. One of them recently sent me a message that included five other artists. They were asking for advice on how to solve an issue they were having with their image. Within minutes a few had responded with advice and direction on the image. As they made the changes suggested they posted the newer images and we'd all continue to give input until the artist was satisfied with the image. Ladies and gentleman, we have a critique group.
The good thing is that your group is able to float. You can custom create your group for each individual problem or circumstance. If anyone you have messaged doesn't want to participate they can leave the conversation of their own accord. Details below!
1. To accomplish this you simply go to the Message icon in the upper left portion of your Facebook account.
2. Select create new message and you will get the following window.
3. Now simply enter the names of the individuals you'd like to include. Type out your dilemma in the message window and either copy/paste a link to your image or upload it to Facebook using the icons in the lower left. Then wait for your reply.
4. You'll be able to see who has read your message in the lower left portion of your message.
5. If anyone wants to leave the conversation they can do so by checking the cog wheel in the upper right and scrolling down to "Leave Conversation".
I hope this proves a great asset for you. It's great to develop these relationships and get input from your peers. It can only help your work grow and get better and let your skin get a bit thicker!