What does it mean when a guy tilts his head while he stares and smiles at you?

That he finds you charming, I would guess.

It depends on how the head is tilted. It also depends on how his neck is aligned. Tilting shows access to certain parts of the brain (eg that access is for creative or memory purposes, social or individual, passive or dominant purposes. There are multiple factors at play:
- the direction of tilt of head (determines parts of the brain being accessed)
- degree of tilt (determines degree of access);
- alignment of neck in relation to the tilt (it can be bent or straight - which indicates the degree of alignment of thoughts - ie dominant, or passive/submissive)
- the rotation of the face in relation to the rest (looking left or right)
- the direction of the eyes

It is complicated to read just from a body language perspective, but then you add in context (which is often missing information, particularly from their past / inner self)

Perhaps if you said "he was looking at me with a sad smile on his face, with his head tilted to the left" I'd say you reminded him of something sad in his past...

However, if he had a lopsided twist to his mouth, and was looking at you with his head tilted his head was also tilted severely to the right and slightly forward - I'd say run.

So looking at you with head tilt isn't enough information.

And context makes such things even more clear.

His head was tilted towards his left side, he had a smile that expressed happiness, and eyes were focused straight on me. Plus, I noticed that he had squinted his eyes while doing so. It wasn't in a suspicious way, but it looked like he was expressing happiness through that too.

I would interpret that as happiness.

Squinting can be for many reasons: short sighted, light in the eyes, irritated eyes etc. Anger (what some associated with squinting)is accompanied by other signs, and not by a genuine smile.

One can be happy with a head tilted to both the right, and to the left. For 90% of people, tilting their head to the left means they are accessing memories (the tilt is reversed, to the right, in 10% of the population, for those 10% to access memories).

In other words, there's a really good chance that he genuinely likes you. But that's what it is - a really good chance. The remaining % minor chance is rather complicated.

Neck crik!

Thank you for your opinion, I appreciate it!

Ah, what skills are missed in the social media world!

He might be a dog in human's clothing. And his smirk is because ... he's getting away with it. Oh... and he might actually think you're a cool person AKA he kind of likes you.

every time I read this

I see

or, he may be having a brain fart

It meant that he was leveling off the rocks that float about inside his head. Squinting meant that he is near-sighted.

Seriously speaking, if you were (or were not) on a date, it meat that he's interested in what you have to say.

Maybe he can only see out of one eye?

If he's rapping the other side of his head with the heel of his hand, he's trying to get water out of his ear.

or

he's an owl.

Sorry.

I think "... and when I looked up..." is the key. He might have been saying "Well? Don't you see Me?"
I once knew two little non-identical twins. When I was paying more attention to the more lively, attention-demanding one, her sister gave me that look.
I think he wanted more of your attention.

Add this to the list of topics to review with your therapist.

I think, that he finds you pretty