Agree that visiting an indoor slope, or dry slope, before you go would be very sensible. Some of them do ‘learn to ski in a day’ style courses, which are really helpful with getting to grips with putting on skis etc.
be as fit as you can.
Ski boots are heavy, but they should be comfortable. If in the hire place they are digging in anywhere, ask for a different pair. You need socks and thermals that will not leave any wrinkles at the front of your leg, as correct ski position is with your shin touching the front of the boot. Getting ski boots on can be tricky. Someone holding the sides open can make a big difference.
take Two pairs of gloves. As a beginner you will fall, and wet hands will make you cold.
take sweets to eat on the lifts. Occasional sugar intake makes a big difference to stamina.
Accept that you will fall, but snow is usually pretty soft, and won’t hurt unless it is icy. As a beginner you won’t be skiing on ice with a teacher.
expect to finish skiing before the end of the day. If you start feeling very tired, stop. Avoid slopes going down into resorts at the end of the day. They will be very busy, and often very bumpy. Better to get the lift down.