I would recommend using any ganja forum from an Internet cafe, from a friend's house, from a hotel, using your neighbor's wireless connection. The more locations you come in on, the harder it is to trace back your real location.
Proxies are a good option but most of the commercial ones won't protect you much... as legal businesses they need to keep logs and can be subpoenaed. There are all sorts of free proxies out there (usually, compromised computers that we "borrow") which work quite well, but you need to know what you're doing to use them. Google for "free proxy" or PM me and I'll send you some links.
Or you can use Tor (
Tor: anonymity online). It makes your computer very anonymous, but your web browsing will also be quite s-l-o-w...
BTW cookies are the least of your concerns. Web cookies are often misunderstood and not very often a security risk. A little paranoia is healthy, too much is not required.
Growver