The right kind of traffic is niche traffic. Who is your brand aimed for? If you really, truly know your niche, then you're halfway to knowing how to attract them with the proper images.
The two pillars of grabbing attention through images are PERSONAL and SYMBOLISM.
An image is personal when it shows dynamic and emotional human beings engaged in some kind of physical contact or displaying an intense emotion -- such as embracing and laughing, holding hands and weeping, etc.
A crucifix is symbolic; so is a swastika. All symbols are powerful, and used carefully with discretion can give your brand a powerful link in the mind of consumers. Think of the Olympic symbol of five linked rings -- it conjures up a host of ideas and feelings.
Find the right symbol for your brand and, as with the better-built mousetrap, the world will beat a pathway to your door.