"How do I pick my correspondences?
First, I must know what I'm doing the spell for. Is it a prosperity spell, a healing spell, a spell to find a new job or maybe to improve communication with a loved one?
Once I determine what I'm trying to accomplish, I hit the books. Within my library, I have several books that index what various colors, herbs, oils and stones correspond with various desired results. I try to be as specific as I can and try to blend my choice of correspondences to better "describe" my desired result.
If I'm going to perform a prosperity spell, what attributes are going to be needed to reach the final goal? Creativity, physical strength, courage? I try to chose some herb or the oil to correspond with those added aspects and keep in mind that most herbs and oils have several attributes. Its is very possible to have an herb with the attributes of both wealth and, say, strength. With one herb you can accomplish two ends.
I leave the color of the candle to the core of the spell. For a prosperity spell, green, a banishing spell, black.
The same applies to the stone I use. I leave it to the core of the spell."
World of Wisdom - Spellcasting
There are thousands of sites online telling you what candles suit with what spells, which oil to use, which colors match your intentions, and so on - but you need to do it yourself. Sorry.
Some intention related correspondences.
Brigid's Haven - common spell correspondences
Weejee's Wiccan magic correspondences
Weejee's essential oil correspondences
Occult 100: spell correspondences
Ghost Dragon's correspondence list
Astrological correspondences of the planets
Spelwerx herbal correspondences
Magical herb correspondences
Common herb correspondences by Darwin
Absynthe's Realm - stone correspondences
Gems and Crystals
Herbal magic - oils
Nature correspondences FAQ
Use the existing sites to check what kind of colors, oils, stones and other corresponding things there is, and what kind of spells they can be used - and then go on experimenting. You really have to test if the correspondences work FOR YOU.
Green has nothing to do with money in my mind. Our money is not green. I think of gold, when I think of money. I think of plants when I think of green. So it might not work for me to use green in money spell.
Naturally you can try the correspondences given on these sites and books, and if it works, keep it. But it might be "wrong" correspondences if your spell doesn't work.
So - have your list and go through just a couple of things every day.
Smell the oil and listen to your associations. Write down what you think. Then look at what you have written down, with the scent still in your nose, and try to crystallize the idea on just one or two key-words. Then, for a week, smell the oil and concentrate on the keywords. And so you have started your own list of correspondences.
The same way with colors, stones, flowers - have it on you, in your hand and listen to your thoughts, memories, associations, feelings...