Points Stacking - Rakuten
[UPDATE] Rakuten has updates since this post: https://www.parkswithpoints.com/p/rakuten.html
Rakuten - Cashback browser plug-in
I have talked about 'Stacking' a few time and this is usually the primary site I leverage because it's very easy. There are some others but I find there is always a catch or minimum payout so I personally stick with the same site as much as possible. You just shop from the site OR use the plugin to active the discount(s) and you can checkout with a credit card and you also earn the card points. It's that's easy...
Example:
1) See a deal TV at Walmart.com
2) Click on 'Activate' *
3) Buy the TV
*If you don't have the plug-in
you can login and start from there website or the app*