Get free products to review on these websites! There are more out there, but I have actually received samples from the following and can personally endorse them.
My favorite sample websites:
The Walmart Beauty Box is a seasonal subscription that charges $5 for shipping. And the Target Beauty Box is a first-come-first-served monthly online offering that usually becomes available around the first Monday of each month. Prices for Target Beauty Boxes range from $5-$10. There are two April 2017 Target Beauty Boxes, and as of today, they’re still available! There is a natural and a traditional box. Both are $7. Get one (or two!) here.
Below left are the contents of the Winter 2016/2017 Walmart Beauty Box, and a recent Target Beauty Box on the right.