I'm having a really hard time doing comparative measurement.

>>3022355
Just focus more and do a light underdrawing of the general proportions, erasing and correcting it when you notice mistakes. Comparative measurement is quite easy and shouldn't take long to learn, especially if you can sight size already.

>>3022355
try comparing things on the page

File: 2017-06-15 22_49_35-chairguy.psd @ 136% (Layer 9, RGB_8) _.png (515KB, 590x646px) Image search: [Google]

515KB, 590x646px

mark out two rough lines on the significant landmarks, i.e hairline and bottum of chin, then one cutting vertically. what's halfway? perhaps, if you're lucky the bottum of the nose, otherwise it shouldn't be too hard to find a shine or a birthmark somewhere. mark that. half it again, you should find some landmarks on lips/eyes etc. now you have horizontal plumb lines, which is easy enough. anything that falls onto those 8 lines you can be almost sure about. mark them in.

the hard part is connecting the angles. stick out your arm and find the angle from, for example, the bottum of the nose to corner of lip, or corner of eye. if the angle of your pencil doesn't match your paper, go back to the landmarks you are certain about, try again.

here's a rough example i've done of the angles you should measure