Suits serve functions, which should be intuitively obvious. However, what styles and colors they are alter those perceptions.
I used to wear a charcoal business suit with chalk strips - same color - with broad shoulders to an elementary school and everyone who saw me thought I worked for the school district's superintendent. People treated me differently and held me to much higher esteem simply because of the suit style, color, and the details. But eventually, the principal and assistant principal started despising me. I would say "hi", "bye", "how are you?" to the assistant principal but she would openly ignore me all the while in front of other teachers. Why? Because I was dressed better than she was. I looked like I had authority and she didn't.
When I worked at concerts where my main priority was interacting with the audience, I wore formal black, narrow shoulders with dark tie. This is what's expected. At no point am I to be a spectacle. The spectacle is reserved for the stage. (I also wore this suit to a funeral.)
A casual jacket is neither a business nor formal jacket. It can be worn casually and can of be various colors and fabric patterns. It must move freely and should be of a lightweight material.
Another important consideration is your face shape, body shape/size and skin color. You must choose styles (also known as cuts) that suit your shape and color that complements your skin.
Shirts
Avoid pure white shirts except for formal occasions. Choose off-white or cream instead.
Topic: Favorite Color Suit?