I am switching from Army to Air Force ROTC (As an AS250). What advice or tips would you give me?

First I'd like to say "good choice"!
Addressing enlisted personnel:
Airman (E-1) through Airman First Class (E-4): Airman
Staff Sergeant (E-5) through Senior Master Sergeant (E-8): Sergeant
Chief Master Sergeant (E-9): Chief
If an NCO has a diamond above the five stripes of his or her rank, they are a First Sergeant and can be addressed as "First Sergeant" and may be called "First Shirt" or "Shirt" in a casual environment.

Use of first names: you may use the first name of people the same rank as you, especially in an informal setting. You should never use the first name of a person senior in rank to you. You may use only their rank as long as it's done with respect. It's okay to tell your supervisor that "the Captain said" without specifying "Captain Smith said." You may use the first name of personnel junior in rank to you in an informal setting, but never when issuing instructions, orders, or discipline. Other courtesies are about the same as the Army ROTC. Officers are "Sir" or Mama", stand when a senior officer enters the room (senior cadet or enlisted may call room to attention), etc.

Your professor probably will provide a class syllabus with learning objectives on the first day of class. The fundamental curriculum is similar to Army ROTC, Service history, organization, functions, leadership techniques, operation planning, how to wear the uniform, etc. The uniforms are different. More so if you're allowed/required to wear the service uniform. AF Service uniform is somewhat plainer than its Army counterpart.

Getting a "FT slot" I assume means a flight training slot. Main considerations are scores on the AFOQT and passing a flight physical. Other factors may be performance in ROTC classes and your professor's perception of your potential as an aviator.

Going in you should listen to your Cadet leaders and professors. Ask questions if you don't understand, be respectful, and avoid "the Army taught it this way. . ." Find a friend who can help you with stuff you don't understand right off like where to put the "bling" on the Air Force uniform. (I had to do this during AFROTC Summer Training for my room mate. He was from Texas A&M and had never seen an Air Force uniform. They only wore the school's uniform. He showed me how to square away the room and I taught him how to set up his Air Force uniform.)

Good Luck!

I think at this time, just listen to the instructors and ask them those questions!

I attended two years of Army ROTC and two years of AF ROTC and like you chose the AF over the Army. I think it’s the best decision I ever made and I spent 28 years in the AF working in Nursing, Law Enforcement, Forensics and Intelligence! My Army ROTC time paid off when I attended US Army Command and General Staff College and the Joint Officer Course, Joint Officer School, Norfolk, VA and went onto 5 Joint Assignments with the Army. Learning US Army history, traditions, career fields will definitely help in transitioning to the AF. In AS 200 concentrate on learning your AF history, traditions and learning to March and call out instructions for leading an element around a marching pad. You need to be asking AS 300 cadets tips for passing Summer Camp. If your university doesn’t have a mini camp teaching you how to make your bed, inspect your and other cadets uniforms, shoes, how to place your uniform properly in a clothing drawer, ask them to run one. Know when you go onto an AF base you need to stay in a uniform group; do not gaggle as in one person walking behind another or fathered ir four people across; do not walk or cut across grass, always stay on a walk way. While in a group, be sure someone is insuring you stay uniformly in line both vertical and across and are all on the same foot while marching. Break your boots in as soon as you get them so you don’t get blisters. Be sure you pay attention to physical fitness maxing your push-up, sit-ups and run! Start getting in shape at the beginning of the semester and take your physical fitness exams seriously. You should call all your NCOs by their rank and last name. And once you graduate and go to your first unit, you should introduce yourself to your top NCO and ask them to mentor your into becoming a great officer to your men and women. This may sound old fashioned and it may be passé but the smartest person in your unit is not your officer boss but your NCO who likely has more time and experience in the service.