A couple of other notes. In a tree-mail, Dave mentioned that 1400 or wider is ideal; 1200 is the minimum. I found that really helpful, and will aim to keep most of them 1500 x 150 after this.
Also, the box for entering a title doesn't limit you, but only the first 20 characters (including spaces) will be submitted. It cut off the ends of most of my earlier titles. Keep the title short and sweet, and add more detail in the "Additional Comments" box.
