Here's one of my faves. I do this trick every month as a type of spiritual tithing, and it has served me well over the years. I do not know where i got the inspiration for this practice; maybe it's in some book or online, although it's not too terribly unique (but brilliant and effective nonetheless).
Prepare a sum of dollar bills. You can use different denominations or just a whole bunch of one dollar bills. I like to use five dollar bills myself, but there have been lean months when a few $1's was all i could realistically offer. You may dress and fix these bills as you wish. My suggestion would be to anoint the corners with a money oil like Money Come to Me or dress them lightly with a complimentary sachet powder. The best bills to use are those which have been sitting under a money-drawing Lodestone, bills that have spent some time simmering on your money altar, or bills which have come from your money pot (a magical vessel where you place your pocket change and cash into at the end of each day). These are considered "trained" bills and will go out into circulation and drum up more money to come your way.
Using a fine-tip Sharpie or other marker, write on each bill the following blessing or make up your own:
"May you be blessed with good luck and health, happiness and wealth."
You don't want to totally deface the bill, but you want your blessing to be noticible.
Take your offerings and leave them places. I like to leave a bill on a grocery store shelf, on a public bench, in a vending machine coin return, amongst other creative places. You do not want to leave your offerings in a place like a public restroom where someone might think it's dirty or undesirable to pick up. It can be fun to find unique places to leave each offering.
You leave each bill with a short prayer and then immediately walk away without looking back. Do not hang around and look to see if anyone picks them up. Just leave and trust that the right person will be attracted to your offering and that the blessing will make their day (it would mine if i found such an auspicious token).
A spiritual truth is that you reap what you sow and you must give in order to recieve. By offering monetary energy without any need for attachment or reward, you send the signal that you trust the Universe to provide for your needs and that you are also open to receive. It really does work.
I'm a big believer in spiritual giving in the form of monetary tithing, although this is a different definition from the more conventional understanding of tithing to your church (although that tithing it cool too especially if you are uplifted and supported by a nurturing church community). The definition of tithing that i subscribe to is that you give a tenth of your income to whoever and whatever feeds you spiritually. This can be a whole range of things. I regularly tithe to websites, writers, as well as teachers and spiritual learning centers. I was once so inspired and elevated by a cab driver, i tithed to him as well (always with a quick explanation or note that this is a part of my spiritual practice so that folks don't think you're leaving them a $50 tip on a cup of coffee by mistake).
Any way, leaving these blessed offerings is another way to give back. We all exchange a lot of energy through money, and it's nice to be on the giving end as well as the receiving end.