As a newbie, I have already participated in some social media campaigns, therefore, I don't think that you really have to be high ranking in order to be able to participate in some. Some social media campaigns requires jr. member rank or higher, and some don't. Social media campaign is one of the easiest campaigns or task that you can participate in here. Basically the campaigns just want you to post or share something about their company or they will just ask you to retweet their tweets, so it is really easy, I suggest you should try it now.