Like @princessmonstertru said, you need that fear sometimes, excitement also feels very much like fear physiologically so don't be concerned about that adrenaline rushing around you, you'll do great.
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Flying is also a scary thing but like many others have said they'll be plenty of people there to help you and they usually have HEAPS of signs telling you where to go. Give yourself plenty of time to get to your first flight so you don't have to worry about missing it (I'd say around 2 hours before boarding time), then you have that whole hour before your second so you'll do fine. Sometimes they delay flights so keep that in mind if you have your friend or someone waiting to pick you up on the other side.
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We're all here to help you when you need it, ask any questions you want because some of us are fairly well travelled and have been on planes a far amount.

Look up terminal maps! O'Hare is huge, but moving between terminals is kind of fun, they've decorated a lot, so if anything you'll have a hard time not wanting to stop and look around.
As mentioned, your luggage will be checked through, so no worries there. As far as packing and checking the luggage at the start, just follow the airline guidance (found online)

Just be sincere and nice with the airline employees and they'll help you out!!

Also fun fact; turns out there won't be any wifi on either flight. Time to start downloading all my books.

Hey Cap, I'm working in the aviation industry. If you have any questions, don't hesitate to ask.
The flights are going to be a piece of cake, believe me.
Moving out of state is a scary thing, but it's a great adventure, too. My career develops in a way that next year I'll probably move from Germany to Canada. Am I afraid of it? Hell yeah. But opportunities are there to be taken, I guess...

See, I'm actually too worried that I'm going to forget something, or miss a flight, or get lost, or stuck to even start being afraid of the planes themselves. I'm not sure that's a pro or a con. Chances are, I'll be so relieved I got on the plane, that I won't be afraid of being in a hundred ton tube shooting through the sky.

God the baggage rules are so weird. Like, i can have a bag in the cargo, one above me, and then a small thing under the seat in front of me, but i cant take stuff down from the ceiling bag I guess, but i cant keep everything i need out???

You can get stuff out of the overhead baggage when the plane is stable and the seatbelt lights are out. You'll just have to pack any loose stuff away during take off and landing.

Ohhh
Huh I did not know that at all. You'd think at least one site would mention that.

So there's "carry on" baggage, which is like whatever stuff you want on the flight and then "check in" baggage, so that's everything else. With carry on, depending on where you're going you can only take a certain amount of liquid, so if you want to bring toiletries with you (which I suggest so you can freshen up during flights), put it all in a clear bag. You can put your carry on above you during flight if you want but you can only take things out from it once you're in the air, or you can store it under your seat.
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My suggestion is to write a list for both your carry on and check in baggage so you know what you have and need. Tick it off once when you put it all out and again once you're actually packing your bags. You don't have too, I just find this relieves a lot of stress.

Would you like a run down of what to expect when you get on the plane? Would that make you feel more relaxed or would it confuse you more?

I mean, i expect to get on a plane and store a bag, sit there for 2 hours for the flight, take my bag, get off, wait another hour, get on another plane for another 2 hours, get off, get my stuff, and then get picked up by a friend, and pass out on the floor of a new apartment because i definitely wont have a bed yet

See you got this

That's pretty much exactly how it normally turns out

But keep in mind the timing of deplaning and boarding. You may land in O'Hare at 1:15, but you might not actually get off the plane till 1:40. Then just try to be at the next gate at least 15 minutes before take off. An hour may seem like a lot but b it will probably be just enough time to get off the plane, get to your gate, and board the next one.

Also fun fact, once I leave my house to go to the airport on March 25th, I will technically be homeless for 5 hours.

Sioux Falls is a great city!

So there's an elderly lady I help all the time, she knew I was moving, but since it was moved up, I went to tell her. She's upset, and this feels so bad...

Write to her!

Welp so turns out that my friend is delaying things, because his home situation has calmed down, so I had to refund my plane ticket. Apparently the extra month is important, sooo... Im not moving for a while now I guess.