Another great thing about bonuses is that the samples they give you are the perfect size. Honestly I don't go through eyeshadow that much and mascara needs to be thrown out every 3 months so it's a waste to buy full size. It's also nice to have new products to try, some of them are so expensive I would have never bought them.
So what do I buy? I love Clinique skincare products, my staples are clarifying lotion 3 (toner) and dramatically different moisturizing gel. Their acne stuff is pretty good too. In terms of make up I use the Almost make-up (tinted moisturizer) in medium. Some of my favorite bonus items are Lancome definicils mascara in deep black and eye shadow quad in chic, Clinique colour surge eye shadow in come heather and Take the day off makeup remover.
I hope this tip helps and that you take advantage of Bonuses!