This is just a short post but I wanted to emphasize the importance of time. The time it takes to read/write a resume, a cover letter, or research or staff a job position is limited and valuable. Obviously there are other things that they could be getting done as well.
I've learned to always keep others time in mind, and be sure to thank them for taking time out of their work day to help me. Also, it's a good feeling when someone appreciates your time as well.