First, you need your ISP to support it. Not all do. A few, like Hurricane Electric support IPv6 at their core and everywhere else. Others have deployed it only on a limited number of routers. What happens here is that your IPv6 traffic is being backhauled via a "tunnel" through the IPv4 Internet to a limited number of switches with IPv6 connectivity. That's not likely to be either fast or robust.
I'm not crazy about those who support IPv6 only with tunnels. What this tells me is that sometime down the road, when the ISP moves to full dual IPv4/IPv6 protocol support, I'll need to change my edge networking setup yet again. That's no win in my book.
And, there are a few ISPs that still haven't deployed it anywhere. If your ISP or Web host is one of the latter, I can't recommend strongly enough that you find another provider. They're not investing in their technology base, and that's a bad sign.
So what you really want is a service provider that provides dual-protocol "native" IPv6 connectivity This should not cost you any more money. Ironically, because IPv6 has been so slow to take off, the ISPs have never been able to convince customers it's worth extra money and, in turn, this has delayed their IPv6 backbone rollout.
When choosing an IPv6 ISP you should consult the SixXS IPv6 deployment page. Another useful site is the IPv6 BGP Weathermap. If you look under "Top 25 Transit/Upstream AS numbers in the routing table," you'll see the top ISPs that are actively supporting IPv6.
Of course, you'll also need to be able to work with the IPv4 Internet for many years to come.
Fortunately, there are many technologies that will let IPv6 and IPv4 co-exist peacefully.
Once you've decided to make the jump, the exact details of how you'll make the leap depends on your ISP. It won't be easy, but in the long run it will be necessary. Good luck!