A photo tutorial.
Please share and comment!
Be sure your primer, foundation, concealer and whatever product you used to set this make up is applied prior to contouring.
My favorite reasonably priced contouring kit is the NYX highlight and contour pro palette available at Walmart.
Use brushes specifically for the purpose of contouring or one you find does the job perfectly for you!
Note: brushes are one item that you should spend the money to invest in a higher end product. They do the job well and last a long time of cared for properly. Be sure to clean them after each use, especially if they are used to apply more than one shade or product.