Before you start to paint your subject, especially if it is commissioned, it is smart to ask your client what they want captured from the subject. There may be something very specific that they love and want represented. If you have a collection of paintings on your website, even asking your client which ones they wanted their painting to most resemble would be very helpful.
This last year, I made the mistake in one of my commissioned paintings by not capturing something my patron loved the most: the hair. I had painted her two Yorkies, and had sent her an image of the finished painting. I had simplified the fur to make it a cleaner look, however she was hoping to get a lot of detail in the fur with individual hairs going each way. The painting was eventually complete, and we were both happy with the outcome, but it would have been completed much earlier if that was clarified before the painting began.
Now before I start a painting, I make sure the following are answered:
How large will the painting be?
What specific feature(s) do you want captured in your subject?
What paintings from my website do you want the painting to resemble
*Very important, make sure your patron isn’t expecting a painting done in a style you aren’t comfortable producing
-What colors would you like (sometimes your patron wants the painting to match a certain room)