It doesn't mean much to me considering I'm a noob around these parts of the interweb, but, I would recommend a paid-only section. Require some sort of pre-requisite / approval process before someone can even be eligible for a paid account.
It will give noobs something to strive for (earning their stripes before they can get a paid account) and it will weed out those with deep pockets that would otherwise be shitty contributors because they'll have to qualify for the account in the first place.
Paid internet marketing forums just appeal to chumps who think if they spend money on free information the universe will owe them some level of success. It's like people who buy "how to write a bestseller" books written by people who've never written one.