Aside from your intent, perhaps you should be working with oils that correspond to the colour and type of candle you are using?
Maybe its the correspondences you seek? Agrippa's Three Books would be helpful, and Culpepper gives correspondences in his books for various herbs, which you might consider mixing with the oils to align better with the candle.
You could also try Michael Howard's book, "Practical Candle Magic".
Tha mi'n dochas gu bheil an eadar theangachadh ceart!