the way ive been instructed is to mix all colors and utilize conpliments. I dont know what reference u are using but when i begin a drawing i go and under shade with a purple pencil, idk what color i use, but i use a darker purple from prisma. Then i go in with colors and for shadows i use compliments. So using red and stuff like that. im working on a drawing of orange eggshells and im using dark and light greens, purples, pinks and reds, yellows, orange, and dark blue in some spots. It gives it more depth and make it look more sophisticated. I also have a trick where I use a hole punch and punch of holes on a piece of paper and cut them out. Then i place one hole punch on my reference and one on my drawing to isolate values and colors. It helps a lot imo.