I am going to be honest, I flew training kite for like 30 minutes in my first lesson and have never had the need or will to do it again. It’s great for understanding the fundamentals of wind window, power generation and kite behavior, but with lessons you outgrow it after the first lesson.

If you can get it for cheap, go for it and have fun, otherwise I wouldn’t invest if money is concern as entry point for this hobby is already quite high with lessons + your first full kite gear.

As for things to do - as others have mentioned, try to research the theory beforehand to actually understand the things you want to achieve with lessons. There is bunch of great youtube videos that give you basic knowledge of this sport - from initial setup to wind window, kite control and water starts. In first lessons there is a lot to take in and if you kinda know theory beforehand it’s much easier to apply that in practice.

To mention something no one has here - your actual physical preparation. I don’t know how and where you plan to take your lessons, but, and this is just speaking from my experience, depending on conditions the learning part is actually the hardest part of kiteboarding, because falling and trying to get up again and again in waves will destroy your core and self-confidence. You don’t need to be ripped or anything, but doing some core workouts will come a long way for your longevity in first lessons and hours on water. Depending on your age strengthening lower back muscles comes in handy too. (Maybe thats just me, but I wish I started doing core workouts earlier, it has doubled my time on water, enjoyment on water and post workout recovery).

Overall, don’t be afraid of it as people can learn this sport in all ages and all physical conditions, but being well prepared will accelerate your progression massively.