I play a lot of netball and have sprained my ankle in the past - very nasty, couldn't walk on it for a day or two. All previous advice is correct, ice, elevation and rest. When I strap my ankle I don't take the strapping as far up the leg as Goodsoulette suggested, but do what feels comfortable. Also, try to use a crepe bandage that you have to strap yourself rather than a tubigrip as tubigrip's don't really offer enough support - they're not tight enough. That being said, don't wrap a bandage too tightly!! When the ankle is strapped (after doing everything mentioned above), it will feel much better. Leave it strapped for a few days, then try to go without.