If you’re just starting out then there’s a chance that you’re using references (I hope so!). Not only that, but you’re trying to match what you see. Then to your surprise, things aren’t lining up no matter how hard you tried! If you get the front view correct then the right view (profile) will be out of proportion. If you fixed the right view then the front view will be screwed and it’s an endless cycle of going back and forth. That was my experience with blocking out the form of this head with a head references in the viewports. What I learned from this is that it’s best to approximate. Don’t aim to match your references 100% perfectly. Instead, see references as guides and don’t be afraid to exaggerate or even go outside of the reference(s).
With this creature, I was modelling and tweaking it without reference but then noticed that things didn’t seemed right. It looked fine when I rotated the model in perspective, but there was something about the front view (Orthographic) that turned me off (didn’t like the look of it). If I tried to tweak the model to look like the one on the right (Perspective), then once I entered perspective mode the model would look out of proportion or out of place. We are used to seeing things in perspective. Even the camera we use has perspective in the image it captures. So, when modelling be sure to check your model in perspective mode.