If I’m just doing an eBook, what size and resolution should my images be?

If you’re only working on an ebook, image quality is much less of a worry than for print because screens require a much lower resolution (so are more forgiving to lower quality images!), but it still pays to be careful. The general guide is to imagine how big you want an image to appear on screen in inches, and multiply that by 100 to find the best size in pixels to upload. So if, on screen, you want a small 1.5in x 1.5in image, it only needs to be 150px x 150px when you upload it (so long as you set it to full size!).