Taking good pictures of your work is essential. Let's go over a couple of tips...
Your phone works just fine.
But if you'd like to flex your camera-skills, you may!
Make sure your photo is at eye-level
and at a straight-on angle.
(Your artwork will look distorted or will have fewer details the farther away it is from your camera lens.)
Outside, in the sun. (warm tones from the sun, cool tones from my shadow)
Outside, on a sunny day, placed in
the shadow of my house or a tree.
Make sure that your lighting source(s) are the same. ie. all fluorescent overhead lights, two desk lamps with the same bulb, the sun, etc. When you have multiple, it will change how we perceive your color choices!
The best lighting is usually found
outside on a sunny day in full-shade.
Most of us know how to edit our photos for social media.
Make sure you:
Crop out anything that isn't relevant to your piece.
Bring up the contrast so we can see marks more clearly.
Try to balance your neutral tones to be accurate, aka. White Balance. (You can hold your piece up to the screen to see how they differ.)