I really want to be sure to help you get the best colors possible, so please follow these selfie tips with a bare-no-make-up face. Don't worry, only I will see it! ;-)
Stand 2-3 feet in front of a window
Face the window (look outside)
Hold the camera at eye level
Turn off your house lights
Wear a neutral shirt
Make sure all photo filters are turned off
Include your face and neck
(Don't take the photo outside - the lighting is not best for your color-match).