I'm wondering...charm an object...I can only assume you mean charge it with a specific force in order to give it magical properties...
There are several ways to do that, first and foremost, the object must be purified and consecrated, before doing any sort of invocation.
Then it should, be proper invocations, symbols, etc being given the specific charge, naming the force and the purpose why that object is being charged.
The best objects are those made of one of the seven planetary metals, semi precious or precious stones, paper, parchment, cotton, silk...basically all kinds of natural objects...manufactured stuff like plastic don't hold the carge very well...maybe it has something to do with the complexity of the molecules....it might be an interesting field of investigation....
I will recomend you a good book, while it's a book on talismanic magic, the same principles can be applied to many objects like candles, stones, etc
"How to make and use talismans" by Israel Regardie
I think you can find it only, it's quite small and easy to read, and it's extremely useful for the average person, as well to the trained magician