First, make sure the theme of the scent matches the theme of the room. If your room is a garden themed room than maybe use a
Gardenia scented candle or a lavender fields scented candle. The purpose of themed candle is to immerse your senses into the theme your room is trying to achieve. Which is why it important you don't pick an ocean scented candle for a sweet treats theme. Some things just don't fit.
Second, keep to the same color palette. You want to make sure that if your room is blue than you should stick to a blue labeled or blue colored candle. You don't want colors that clash with each other. You want your soy scented candle to be in the room, but not noticed. It needs to secretly add the right ambiance to the room without drawing attention.
And that's basically all you need to do. Simple, but important. The next time you go out to select a scented soy candle for your room keep these tips in mind. Any room you pick will be much better now that you are aware of how to make the most of your soy candles.