if it's in your hand and magnified, there's not much you can do about the added blurriness from shakeing the camera - ever so small movements too.
the desktop ones are the best - digital mircoscopes. if you can get that steady or mounted on something (and your phone mounted on somthing) then, you can position and take a picture that will come out better.. if you are holding it, it is going to look like crap.
use normal lighting, if you can, not your grow lights. A black background can help it pop out in the picture too. although if zoomed in,there's no background, so that's more for normal pictures, lol.