I've looked at your last couple of posts. If you keep the size of the image so it shows on a typical display (600 pixels on the longest dimension) then they are as large as possible without the user scrolling. Is that what you mean?
The rest is sharpening correctly, using srgb for the jpg image profile, and selecting a lower level of jpg compression to minimize artifacts.
If people did not sometimes do silly things, nothing intelligent would ever get done.