I tried making one but it turned out to be really small when I uploaded it. Does anyone have any advice on how to make one for here?

Use  Tinypic.com, and set the upload to TV monitor. It works when I do it.

http://postimg.org/ also works too when you set it to do not resize my image

Use Tinypic, you don't even have to paste the link once you've uploaded it you can drag it over between tabs and drop it into the signature box

If you want, you can also upload it here on the forums. There's a section for that. It's where my current siggy resides.

thank you all for your advice! I really appreciate it, it was very helpful!