First off, and I should've added it in the tutorial: The pupil here is stylised to give more expression. In a completely realistic bird, it would be placed in the center of the eye, about where the lines cross in step 2.
A TINY ADDENDUM TO MISTAKE 2: The beak is in one piece. How the hell's the bird supposed to even OPEN the beak then, when both upper and lower beak are fused together? Just imagine how it'd be if your own jawbone was fused to your skull, and avoid drawing one piece-beaks at ALL COSTS in the future.
Might also be an idea to look at this comment: [link] for more details on mistakes 1-3.
This is the combined result of the following:
-- Getting lotsa faves on an old and outdated tutorial
-- Seeing lotsa mistakes, and yes, a great many of these principles hold true to other birds as well. 'Specially the oval head shape, connecting the beak to the skull, the curve of the lower beak and resulting fluff, the diagonal line which the eyes and nostrils line up along, and so on. Manipulate to your advantage.
-- Drawing burds
So yes, I hope this can and will help some. If you've got any questions, ask, and if you make something with it, I'd be happy to see the results!
As a last note, I have not added nares at the lower beak because I add it when I colour the burd, not when I sketch it. Just so ya know!
More burd/gryph resources can be found here: [link]