GIFS look grainy and pixelated. Help, please?

I'm sure this has been posted before but I cannot find a link to it - Whenever I attempt to make gifs with ImageReady 7.0, they come out looking grainy and pixelated, whether they are black & white or color. I have tried making them smaller like 225 x 120 but it doesn't help. (example one ; example two) How can I fix this? Thank you for any help :)