If you enjoy review products for heavy discounts, free, or to even get paid to review - Tomoson is is a great starting website. Join by clicking here. You can browse through many different categories based on if you want the item free or heavily discounted. Once you've reviewed a lot of items and receive decent feedback, you even have better chances of applying for items you will be paid to review.
At the bare minimum you will need an Amazon.com account. Each product lists along with it what you will need to do to receive the product. Every one requires you post a review to Amazon.com. Some, especially the better products, require that you post to various social media sites like Facebook, Instagram, Youtube, Twitter etc. When you apply, you can let the company know what sites you'll be willing to post on that they haven't listed as a requirement, so that you can have a better chance at receiving the item. If chosen, they will send you a code that marks down the product to the stated price or so that it is free. You will use that code to purchase it through Amazon. I have found that it is one of the better websites for beginners to get started on. I was accepted for a product immediately when I joined.
See the picture below for an example of how products are listed and how you can tell what is required of you.