I been doing what he's talking about for years. I figured it out on my own. I always get at least 2-6% cash back on everything I purchase. The only bill I can't pay with a credit card is my rent because there's no way to do it without paying at least 2% extra minimum.
I use these cards.
Citi Double Cash 2% on everything uncapped (this is my general card for whatever doesn't apply to the below).
Chase Freedom and Discover It 5% back on rotating categories usually gas, dining, warehouse clubs, and home improvement.
US Bank Cash+ 5% back on selectable categories. I always pick electronics stores (I shop at Best Buy a lot) and utilities (covers my power and gas).
Amex Blue Cash Preferred 6% back at grocery stores and 3% back at gas stations (has a $95 annual fee but I spend enough to cover it paying itself).
Amazon Prime Visa 5% back at Amazon if you're a Prime member.
This year I plan to get the 3% back Capital One Savor card for dining when none of my 5% back cards covers that.
Now that pay a mortgage using a line of credit stuff that other guy is talking... I don't know about all that. I looked into manufactured spending but the shyt is too complex for me. It's basically spending your cash back cards credit on stuff that you can easily turn back into cash to pay the balance back.