Digital Photo printing

Is there some sort of guide to follow, as to how big a print can be, according to the number of megapixels? I know that MP doesn't mean everything (it's the quality of the pixel that matters) but, how big a print could I safely print, at a good, high quality, from, say a 6.1mp camera, as opposed to a 10mp one?

Well, a fairly standard print resolution is 300dpi (dots per inch). If you set your picture's resolution to a matching 300ppi (pixels per inch) that will give you an idea of a full res shot. For example, shots from my 10mp camera at 300ppi works out to an 8x12 inch print. Of course you can always go to 250ppi (maybe even 200ppi though I haven't tried it) for acceptable results. I've also seen 24 to 30 inch prints from 6MP, and those shots upscaled in software.