I have a boxer, grew up with them and they are hard work but rewarding. If you put in the time you will have a wonderful companion.
My tips:
By a book on boxers, read, re-read and read again to get a good understanding of the breed.
Second the insurance, aside from cancer they have bad bones in general (that's inbreeding).
Third, do not wait to start puppy training classes! I spent about 4 hours a day every day for months training mine, the benefits are that she obeys all my commands, she walks around our village to heel OFF the lead. I can not emphasise enough that putting in the work now will be of benefit.
Buy a crate, this should be used as their safe space, somewhere it can go when it needs space and familiarity...
Boxers only destroy things out of boredom, there is absolutely no need to have a dog that destroys toys or your possessions. Make sure you exercise them well, until recently I walked mine 3 times a day, lots of play in the house too.
Boxers like routine, feed and walk times should be kept the same each day.
Another boxer trait is their incredibly weak stomachs. Keep food bland and consider a biscuit diet, discuss with your vet.
I'll be honest, I see lots of owners being dragged around the parks by their boxers and hear lots of stories of destructive behaviour and honestly, there is absolutely no need for any bad behaviour. If you don't have the time, energy and inclination to train and play, then this is not the dog for you.