No spell is 100% guaranteed. Any one who tells you otherwise is misinformed.
At night before you go to bed, and to be repeated every night thereafter, take all the cash money (paper money) out of your wallet and set it out on a surface. Pray over it that as you spend the money during the next few days, that it will be magical "hunting" money that will go out into circulation to "hunt" out more money to return to you.
Anoint the center of each bill with your oily thumbprint that you've applied money-drawing oil to, or skip this if you have no such oil (it's worth the $5 investment). Write the words "Return to Me" or the acronym "RTM" in each corner of each bill. Sign your name over the signature of the treasurer, which you can find on American money - sign your name somewhere else if there's no official signature anywhere on the bill. Sprinkle the bills lightly with ground Cinnamon, stack them, and use a magnet as a paperweight that will stay on the stack of bills overnight. You can anoint the magnet with money-drawing oil too. Pray over the stack again - or "charge" it, whatever. Repeat each night.
Spend the money as you would normally. You do not have to repeat the process on leftover trained money - just add it to the bottom of the stack to recharge.
If you've ever gotten money that has certain symbols or names on them, this is why. Plenty of people, at least in America, fix magical hunting money. It's lucky to get such money. You can just sign your name next to the other person's signature, and you both get the luck!