I need help with my embouchure on the French horn.?!

I need help with my embouchure on the French horn.?

I've been playing lately and have noticed a few things with the way I play. One, I don't articulate notes easily and clean like I should. Two, I strain my mouth to get high notes. And Three, I look in the mirror and see one side firm but not too much of a smile, and the other side appears really loose, but I feel like I'm using my muscles more on that side. That's probably too confusing for anyone to understand but I can't find anyone to help me. So I'm only trying here in case someone does know.

Hi, how long have you been playing?
It looks as if you're forcing the air using what's called valsalva maneuver. This is an incorrect way to play the french horn. To correct this, breate low using the disphragm and form a slightly puckered smile. Tighten the embouchure of both sides of the lips, and use make sure you're sitting straight up. This helps to keep the airflow going. I know this is hard and probably takes a lot of practice, but I know you can do it. Try not to practice high notes at this point. Range comes with endurance, so you probably don't have enough of the lips muscle to play in a relaxed manner. Keep practicing, and it will definitely pay off.