If you get airsick easily, then I recommend mechlazine to dramamine

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If you are getting sick from worry, you shouldn't, as there are lots of people who do this the first time, and many don't even think to figure it out ahead of time

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The security piece has been mentioned, so I won't go into that, except to say you'll need to take laptop computer out of their bag and place into a tray by themselves. Passengers under 10 and over 75 don't need to take off shoes and light jackets, but the rest of us do, so wear socks. Also, don't rush and try to suppress the feeling of being rushed in the security line. Take your time, as rushing may cause the line to move slower when you forget to remove something from the bag. It is stressful, but there will be plenty of time if you show up early. if other passengers are in a rush, then that's their problem for not arriving early enough, and the TSA will get those through who are actually going to be late (they won't be in the family line).
It would be helpful if we knew which airline, as they can be basically grouped into three categories: legacy (Delta, American, United), low-cost (Southwest, JetBlue, Frontier), and super low-cost (Spirit, Allegiant). They all have different rules, and it is worth your time to skim the airline's Conditions of Carriage, as it lets you know what the airline expects.
Generally our family's carry-on bags look like this: DD has a small kid's suitcase with her stuff in it (crayons, teddy bear, neck pillow, activity books, etc), DW has her laptop bag filled with stuff...Lord only knows what..., and I generally have a proper carry-on bag to go in the overhead bin with two days of shirts, undergarments, and one extra pair of pants for each of us, as well as DD, DW, and my 3-1-1 bags in the outer section (for easy removal at security). We also keep a swimsuit for us, if we are heading for a place we would use it.
Each person can have a personal item, so DW has a purse and I have my standard backpack with nook, snacks, magazine, etc. which goes under the seat in front of me.
Let us know what airline, so we can give suggestions on boarding, seats, etc.