Most people have signatures with an image or two. This is common, so there must be some rules regarding signature size:
* Image width should not be more than 500 pixels
* Image height should not be more than 400 pixels
* If you have an image that is 500 x 400 (width times height), you cannot have another image in your signature (also, VERY little text -- 5 lines tops)
* You may have two signature images if the height of both does not exceed 400 pixels in height
* Preferred (but not required) image size: 470 x 150
If your signature is within those guidelines, you should be okay.
NOTE: Nudity is not allowed in signature images.
Signatures and their content is shown after each of your posts, and therefore the text must not be offensive. Like posting, it cannot involve racism, sexism, or insults towards someone's sexuality.
The amount of text you are allowed to have in a signature is not by character limit, but by size. If your text makes a user scroll down to reach the next post, it's probably too large. Try to keep your signature image and text a reasonable size -- most have text and a banner, so be sure not to break the banner or text rules.