Whenever I upload a preview pic, it always has artifacts - all those little pixelly things all over the place. I usually save it as a jpeg, but as a maximum quality on photoshop. I also try to keep it small or at least proportional, so the condensing doesn't affect it.

Can someone tell me what I should do to make a clear, clean preview image?

Next time, try .PNG instead of .JPEG. Many professionals here use that because .PNG shows the picture much clearer than the other format ever could. Try it and see for yourself.
Hope that helps!

I believe if you are uploading a jpg, DD will try to maximize the filesize which reduces the quality. It isn't normally a problem, except in a case like yours where you're trying to keep the text readable.

I'm not sure wheter the site will accept a png for the thumbnail image- I know it won't take gif. But you can just give it a shot. :]

Well, it accepted a .png, and it looked kinda better, but not that good. I have a different idea though. I remember when I didn't have a preview pic, DD took my first page and compressed it, and did a good job at it. I'll try deleting my preview pic and see what happens. THanks tho!