Apply an icepack or a cold spoon on the area. This will help reduce the swelling and redness. Be sure to do so as soon as possible and as frequently as possible.
Another popular method is to use a toothbrush or comb and gently brush the love bite. It sounds ridiculous I know, but people swear by it! All you have to do is brush the area around it which will stimulate circulation and reduce the redness and swelling after about 30 minutes. The first 15 minutes will make it worse - so don't panic!
Apply Vitamin K cream. It is used to reabsorb the blood that is stuck near the surface of the skin, which causes the love bite.
If all else fails, try the coin method. It is the most painful, but it's a desperate time, right? First, stretch the skin flat by pulling both sides of the love bite away from your neck, then take the edge of a coin and scrape the skin outwards. Press hard enough, but not so hard that you break the skin. There will be redness from the scraping, but it will go away much faster than a love bite will.
For next time, avoid getting sucked-on your neck!