You need to donate, and depending on how much you can get certain features.
All tiers come with access to a special forum and custom profile designs. But there are some features only available to a certain tier and above.
Tier 2 and up comes with a blog, Tier 3 and up comes with larger avatars and profile pics, Tier 4 and up gives you extra PM space, Tier 5 gives you even bigger profile pics and a personalized email while Tier 6 gives even bigger avatars.
I got mine from a recent event back at the end of September, and I was initially granted Tier 4 Supporter the day after my birthday. I only got upgraded to a Tier 5 last weekend after someone gift donated for me.