Established members are members that have a few extra features because they contributed something useful to this site. It's actually not hard to become an established member, but it does require some minimal effort.
Basic requirements:
Has posted at least 30 post/replies
Has posted at least 1 thread/topic started new!
Has been registered for at least 30 days
Maintain to keep your account on Established Member status:
Has posted at least 5 post/replies last 30 days
Has posted at least 1 thread/topic started last 30 days new!