Try to visualize it as best you can. It doesn't have to be perfect. Your intention is very important here and everything will work. Practice your visualization every day and it will get better and better for you over time.
In this link you have a picture with an aura around the person. I hope it will make things a little easier for you:
https://www.joyofsatan.org/www.angelfire.com/empire/serpentis666/Human_Soul.html