What you do, to optimise your illustrations/jpg files for the web in Photoshop. Mine look terrible and pixelated when I try "Save for Web” in Photoshop. My jpg files print out on photograph paper perfect at 300dpi, but I can’t figure out how to get the same result for the web.
That's too general a question. Please post an example that can net you more specific advice.
My VERY general suggestion is to prepare the image at a higher pixel count than it will need for its final use, then downsize as nearly the last step.
You do realize the resolution is different between print and the web right?
Depends on your web device some web displayed these have the same resolution as a typical print.