Trying to keep the file size down

Good morning, everyone. I am finally getting around to posting pictures of my coins and I am running into a file size problem. I am having to use a 7.1 Megapixel camera, setting the resolution to it's lowest setting to get the files small enough to post.

Does anyone have a suggestion to getting better resolution pictures while keeping under the file size?

I attached one of the pictures that I have taken. Not bad, but the pictures come out much better with my wife's camera with a higher Megapixel count.

Thank you for your help and happy collecting!