My first inclination that this had been taken from a GIF image is because there are very few colors used in creating the image - this is indicative of a GIF or a very badly reduced/optimized JPEG. Either way the colors appear to number fewer than 64, and a JPEG naturally has over 6 million different colors. Perhaps this is caused by editing software and not the original image capture. Not knowing much of anything about the equipment or software you are using, I cannot really help you with making it work better for you. Suffice to say, the following is true:
1. JPEG is always the setting you want to use in saving your images.
2. Web images are viewed at 72 pixels per inch. Anything more than that is wasting space.
3. Optimization can be reduced by as much as 50% with good software (or the right website).
4. Pixel size for your images at 72 pixels per inch should be no more than 800 x 800. This is plenty large enough.
I just did a search online and found a large number of JPEG optimizer websites where you upload your image from your computer, and it spits out the result for you to right click and save. Maybe this will help...maybe not. but here's one of the search results:
http://jpeg-optimizer.com/Another thing that could help is Adobe Photoshop Elements. You can get this for under $100 online, and you can use it to edit your images in a program that the professionals use. I fear that many of you use cheap (or free) software, or that you use the software that comes with your camera or scanner, and they are - well - not good. Adobe also includes (free) an image organizer that you may find helpful.