Well what I've learnt while I was active on dA was that if you want comments you have to promote a lot your works... and even by doing that, though, you can't be sure to receive many! All I can suggest you is to try to get involved into contests and into the community (forums and chats).
I have only one teeny weeny problem with that. It's hard to self-promote without people saying that you're whining for attention, and that could endanger my reputation a bit. Some guy called me a troll once for putting "Check out my gallery!" in my signature. By the way, I didn't know DA had a forum…can you please explain how that works?