Lust powder is very useful to have someone lust strongly over you. It can also be used to heat up a relationship which is already happening! to use it you would simply sprinkle it onto the seat where the person will sit, onto the bed, or rub some on your hands and touch the person. You can also of course use it with candle spells, though it does work much better in person. Another option is to dress a letter with it, by rubbing it into the letter, then shaking it off so the person doesn't really wander what is up.
This one should not be used on unstable people btw, or they could become obsessed with you; no this is not a good thing.