My suggestions:

Book a table well in advance at the Trattoria La Pesa dal 1902 nearby (they sellout quick) and eat dinner there. Leave an hour before the game starts and walk up.

Go to the toilets at the restaurant so you dont have to go at the stadium.

Try to get a 20:45 game so the stadium is light up it looks really majestic from the outside with the spiral lights.

Dont expect to go to the toilet or buy snacks inside the stadium. Once you’re seated stay there until end of game.

Buy some snacks beforehand or in the street food places outside the stadium. I dont think they let you bring in bottles with lids on so keep that in mind.

I recommend booking seats in the central red section (pic related) first floor (letters) or second floor, avoid third floor.

The seats are quite steep so if you go for second floor red be aware of that, it took me a bit of a surprise its like a straight drop down.

When you leave the stadium to go back home it is quite chaotic with the public transport. And getting a taxi is next to impossible as I remember it. Maybe plan to walk a bit into the city after the game.

You can use sharenow cars around the city if you are signed up to their app sharenow so maybe try to do that if you want to drive around Milan you pay by the minute then just leave the car when you park it. You then need to try and find one nearby with the app to use again.

No one beats you up or anything like that. Worst part is just trying to find transport to get back home after the game because a lot of people.