Be careful when editing a JPEG image; it will lose quality each time it is saved.
JPEG is a lossy compression type, meaning it loses quality and information when saved. This helps reduce file sizes. GIF, PNG and BMP are lossless compression types, meaning there is no loss in quality when saving. The downside of this is a larger file size and less file support; most websites that allow image uploading will only accept JPEGs.
Make sure your image is in the sRGB (standard RGB) color space (Edit > Convert to Profile > sRGB IEC61966-2.1). sRGB is the color profile supported by internet; images in different color spaces will display dull and incorrect colors on the internet.
I always add a copyright to my images (File > File Info) before saving. I’m not sure how this copyright will stand up in court, but its better than not adding one at all.