Any tips welcome for a first timer!

I'm going with a friend on 30th of December, and it will be my first ever visit to any theme park! I am really very excited and always wanted to go to a theme park since I was a kid, but didn't get a chance... In my 30s now but still, woo hoo :D I'm not from Germany, visiting a friend that lives nearby hence the weird date... I'm kinda on a budget but would love to see and do as much as I can, so any recomendations or tips would be very helpful!