If it is cold outside, there is always the turtleneck. Also, since scarves have become very trendy, almost all year long, you can use this fashionable accessory to hide you love mark.
Another viable option is makeup. First, use a primer on the area. This will help keep the cover-up you will use next to stay on longer. Now, apply a concealer that closely matches your skin tone so it blends into your skin. Finally, smooth on your foundation and work it into your skin, just like you would on your face. You can finish this off with powder that is sweat and water-resistant.
Take an icepack or wrap some ice in a towel and apply it to the hickey as soon as possible. Gently hold the cold compress to the skin for as long as you can (up to 20 minutes), remove for several minutes, and then apply it again.
Gently brush the area with a new tooth, the stiffer the bristles the better. This helps increase circulation the the area, but you must be gentle, pressing too hard can make the hickey worse. Wait about 15 minutes and apply a cold compress, as above.
Use the edge of a quarter or half dollar the scrap the hickey. Unfortunately this is the most uncomfortable method but can provide quick results. Hold the skin taught with on hand and use the other to scrap the skin in an outward motion. Push as hard as you can without tearing the skin. Your skin will red from the scraping, but that will go away much faster than a hickey.