Signatures should be no wider than 500 pixels and no taller than 400 pixels. They're pretty lenient here about that stuff.
That's really only there to make it so people don't have, like, giant murals in their siggies, followed by their 52 clickables and 4 sonnets about how they love pizza. ; A;
_________________ "Women don't want to hear a man's opinion. They just want to hear their opinion in a deeper voice." - Jeff Foxworthy