You might want to look into some more reference that has some of the topographical information you might be able to show on such an image, but then it all depends on what your goal is for this. Are you going for a realistic sort of image, or are you going for a stylized / exaggerated feel? You might not be able to see mountain ranges in that reference, for instance, but it might make the image more interesting to look at if there were some more speciic details on the globe. Right now what you've got in Spain is just noise, really. Are there mountains there? Forest? There's a dark spot in Africa with some more pixels dotted around it... what is that spot? It might be more appealing to visitors to see something that would represent what those areas actually are. The piece is also really large, which is great if you think you can pull it off. I don't think I'd be able to. You might want to think about cutting the resolution in half, but then if this is a website image and you want it large then more power to you.
For the record, the bit you call Alaska is actually Greenland + some of Canada. The little white dot below Greenland on the ref is Iceland, which you should add. Madagascar and Japan should probably get on there as well, tho I'm probably just getting ahead of myself.
Bottom line: If you're gonna try to make this look reasonably 'real' or detailed or accurate, I'd suggest getting some more ref so you'll know when to break from this particular reference and add maybe the odd detail that might not be all that evident on that image (like the Nile, which is a pretty huge landmark, but isn't very easy to discern on that ref.) And I'd suggest blocking out the land masses - especially the shorelines - with a lot more accuracy before you start jumping into detailing much of anything. Getting the outline and proportions of a landmass right is key to making it recognizeable. India / China / Russia shoreline is pretty far off, The mediterainean area could use a lot of work (Italy is there, but doesn't look like Italy, Greece is missing entirely).
Simple world map:
http://info.comegoogle.com/phone/world-map.html