Prosperity magick is often done on Thursdays, using a green candle. If you want to add a stone to the mix, many of the green stones, like malachite, jade, or aventurine, are also associated with prosperity.
One of the things I always suggest when doing prosperity work is to keep an open mind. If you ask for one specific thing, like money, you might or might not get it. But if you leave room for the Universe to improvise, you might end up getting just the right thing and the right time to fill whatever need you have.
When I am going to do this spell, I often take a green votive and using the tip of my athame or a toothpick, scratch a few rune symbols (such as Uraz and Gifu) into it, along with my initials.
God and Goddess hear my plea
Rain prosperity down on me
Bring in monies large and small
To pay my bills, one and all
Money earned and gifts for free
As I will, so mote it be
Note: If you are concerned about getting your prosperity in a way that is less than positive (a relative dying, for instance), you can always add at the end of this or any other spell: For the good of all, and according to the free will of all, so mote it be.