I am so excited for you! I fucking love yoga so much. I am so far from accomplished but I've been doing it for a while now. I'm not good at negative advice either, but just some stuff (this may seem obvious too): Wear tight to medium loose clothing. I prefer tight pants and shirt simply so when I go upside down it doesn't fall and flash everyone.  If you fall, no one gives a shit. So go ahead and fall, but make sure you get a blanket under you so you don't break yourself. Use blocks. I know up the thread someone said you shouldn't look around during class but I honestly do ONLY to make sure my form is right. I think this is ok. It's best to do this to compare to the teacher when they're not walking around. Feel free to ask the teacher questions though, they should be helpful and nice because 99% of yoga teachers are hippie dippie people and are into helping people. Bring water. Rest as often as you need to. You should ideally take what you need away from the class, and that includes using your body in a way that is best for you. If that means you can't hold a pose as long as an instructor wants you to, fine, especially for a beginner. I would suggest really concentrating on your breath and flowing with it as much as you can (you'll understand this better after class). Sorry none of that is negative haha. After being a teacher I'm pretty bad at negative advice because I was paranoid about making my students cry after actually making one cry.