Graduate Secretaries make sure forms get signed, they can put your interdepartmental application at the top or the bottom of the pile, and they can smile and be friendly enough to brigten your day - or they can rain on your little graduate school parade.
When you arrive at your program, be sure to introduce yourself to the staff of the department. Treat them with the same respect that you treat the faculty. This is crucially important. That can turn a form being two hours late from being a, "no problem, sweetie!" to a, "tough shit!" moment.
Here is another quick tip: over the course of the next several years and months, the staff may offer hints that can help you and the department Physics, History, Anthropology or Sociology (or whatever else) Club make nice at the end of the year. They all seem to like wine? Wouldn't giving them a reasonably prived bottle for Christmas be a nice gesture? They like flowers and all happen to be mothers or fathers? Wouldn't a Mother's Day flower arrangement brighten the office. Offer this suggestion to the Sociology Grad Student Club and see what they think.
More important than the nice little gifts or gestures, just be polite, treat everyone with respect. You never know who you will need to call when you need a favor.
