This picture really helped me when I started to learn how to contour:
The parts that say highlight are meant a lighter color, while the parts that say contour should be done with a darker one.
I tip that one of my friends taught be is that you don’t actually have to buy those expensive contouring palettes, eye shadow works just as well. It’s a cheaper alternative to get the same results. So before going out about buying anything, look through your eye shadow palettes for white and dark brown shades.
Another tip is to blend really well! You don’t necessarily have to go for the beauty blender, you can use your foundation brush or another wide tipped brush.