A lot of new threads are made constantly about several topics- 'When's the next language coming out', 'Why isn't this fixed' or whatnot. Many forums have sticky threads set by the moderators that are always the first two or three on the list but address these issues. It might cut down on the redundant threads created by new users who might get jumped on a bit by grumpier students.
A while ago I had a look through the individual language forums and saw a lot of discussions that had been down-voted, sure, they were basic questions that had been answered before and would have been answered in the lessons themselves had the person kept studying instead of pausing to ask but in most cases the person asking had just discovered Duolingo and was potentially learning a language by themselves for the first time ever and they were excited to be here. These people don't know that their question has been asked before or that it will all make sense soon, all they get is a not very warm welcome and discouragement from asking valid questions in the future, which is unfortunate because we were all new to languages and to Duolingo once, we should know how they feel. And then there's everyones favourite "you should introduce -insert language- next!" threads...
I think a few stickied threads about common questions/problems/discussions could reduce the number of new discussions that pop up on old topics and give a warmer welcome to new users. Also, I've been a member since the end of last year but I'm still sometimes curious about the responses to some of the "annoying" questions.