It's a tough subject, for me. I always try to remember that DF is in alpha, and that it doesn't even have all its bones in place yet. From that standpoint, people wandering in and asking for interface or balance adjustments as though these were Starcraft or TF2 forums reek of ignorance and arrogance, thinking that toady will take a break from welding the frame together to pad the seat a little more for the kids who want to pretend they're already driving it. I'm always offended by that, to some extend, even though I know that the community is a big part of DF's growth. We depend a lot on each other, for learning and support and good times, and a large portion of the forum and community is already devoted to making suggestions about how the project should progress.
Read the eternal suggestions, peruse the bugtracker and search the forums and wiki, and I'll bet dollars to doughnuts that what you want has already been asked for. Rolling up and saying, "You know what this game needs? A comprehensive manual and a guided tutorial and proper documentation and three distinct difficulty levels and better graphics and more mouse interface and better skill management and a bug-free military and no more unkillable forgotten beasts and a better framerate and wheelbarrows for the dwarves," isn't going to make you any friends, and if that's your first and only post on the forum you're going to be labeled, "Nubtard who thought this was a finished AAA title and didn't bother learning about it before he opened his mouth." It's kind of like wikipedia. Sure, anyone can weigh in, but if you've got a Ph.D and some published works on the subject, people will respect your input more. Lurk, learn, play the game as is (Newb pack is a great starting point. I've been playing for years and I use it now, because it's so easy to just download and run it.) and when you get all the jokes, understand other people's complaints and have seen the bulk of the content, you can go ahead and voice your opinion in a useful way.
TL;DR: We can be civil and productive, but if you just bust into the DF community and start telling everyone how it ought to be, wear asbestos undies.