Tips for marking seams?

Hello! This is either my first or second post on this forum (I’ve had this account for a year but never used it lol) so forgive me if this isn’t the right area… I’m not new to modeling in Blender, been doing that on and off for the past 4 years however I’m pretty new to UV mapping and texturing in blender. I know how to do both, however I apparently do not know how to properly make UV maps for meshes. I’ve modeled, mapped and textured a dragon’s head:

But from what I’ve been told by my friend, this is not proper mapping:

And I have to agree, the ears are differently sized, and as you can see in the first image around the top part of the dragon’s head to the right, there appears to be a little white line right there. If I try to paint that it’ll bleed across the image into the horns, another tale-tale sign that I’m not doing proper UV mapping are those oddly placed 1-2 pixel thick black lines found randomly in the image. I’m not really sure what all I’m doing wrong with my mapping, but I’ll greatly appreciate it if someone will take a look at the .blend and tell me what I’m doing wrong.

.blend and .blend1 files: RBX_Dragon_Head.zip (692 KB)

(Also how do you make a spoiler on this forum?)

1, Please, for the love of God, DON’T USE NGONS, you’ll never be able to properly unwrap a mesh with ngons.
2, There’s too much difference bw your base mesh and your subdivided mesh, so before unwrapping, apply the subdividion modifier at least with 1 level.
3, Make new and better seams.