I start from the first step that I made even before I landed in Osaka. To get tickets you need to go in the Japanese version of the website, use Google Chrome, so you can sort of translate what is written if you do not know Japanese, and be careful, there are 2 different options of obtaining tickets, on email and at the ticket booth. If you choose 2nd you'll have to stand the line (that was my mistake). I paid easily online with MasterCard debit card. Also, there are some other things you can book there, like Halloween buffet that was available in October. But if you can not do that you can get tickets at the airport information post, where they sell tours, There is a line also but not that huge)
I got 2 day entry tickets and good that I did, for the first time it's easy to get lost and confused, plus 2nd day was really rainy. There are maps at there entry, get a couple of them, you can lose them (you can always ask a worker of the park for one) or if it's rainy you will definitely get them wet, so you need an extra.
At the first day, I arrived at 7.30 in the morning so I could get the ticket and line at the entry was already pretty big. So really If you have to pick up your tickets at the booth and you going with the friend, use It to your advantage and make your friend to take the line to the entrance as soon as you arrived.
After you entry early in the morning, most of the people gonna be RUNNING to the Wizarding world, and there also gonna be a line, if you are eager to go to a ride, run or come much later or get an express ticket (but it costs extra). The average stand in the line at HP is about 2hr. As for the other parts of the park, lines are not that horrible, use single rider line if you can.
There is also an information stand, with online info on how long is stand there, near the restrooms between China restaurant and the Jurassic world.
Now attention to all the movie and TV fans-collectors out there: There is a signed posters and photographs gallery and everything is available for sale. It's more expensive than online but is much safer since they give the receipt and auction certificate (plus Japanese people are much trustworthy net some guy from the web in my opinion)
As for the food, if you not planning to spend much on it, bring something from Family Mart or 7-11 with you) But if you do want to try everything come hungry! I loved having breakfast at wizarding world
I hope my experience will help you prepare more for your trip and make it more plausible) Thank you for reading)