Whatever you do - call, use Touring Plans fax service, etc. - it's best to use positive requests. Don't say "Not near an elevator" or "No connecting door" because it's far too easy for the assigner to overlook the "not" or "no".
Also, if you have more than one request, it's best to state which is the highest priority. If you have multiple requests without you prioritizing them, the assigner doesn't know which is most important, so you may get your lowest priority or none at all. Example: Lest February I stayed at Sports. My requests were phrased as "I would like to request: 1st priority - Surf's Up section; 2nd Priority - top floor; 3rd priority - corner room." That way the assigner knew to start with seeing if there was anything in Surf's Up; when there was s/he could look for top floor; when there was s/he could look for a corner room. I got the first two and was 2 doors down from a corner. Practically perfect. (Had there not been anything in Surf's Up, s/he would likely have gone to see if there was a top floor in the other preferred section.)
Also, if you are arriving early, you can designate on the WDW request page if getting in a room early is a higher priority than your requests. I also include that on my Touring Plans fax - either that I'd rather have a room early even if that doesn't meet my requests or I'm fine with storing luggage and waiting if it means I'll get one or more of my requests.