1) Be familiar with what is and is not allowed in a carry-on. They should learn this before they pack, and not at the airport. If they want to carry a bag on board, they should know what to put in it and how big it can be. They should also know what *not* to put in a checked bag (generally, expensive electronics, Li-ion batteries, and/or critical medications).
2) Arrive at the airport at least 90 minutes early. Generally, for a domestic flight, this is too early, but if this is literally their first time, they will need extra time to be familiar with things.
3) Wear comfortable clothing and minimal jewelry (to have less to deal with at the security checkpoint). A backpack (or purse) with room to easily stuff some things (like watch, phone, wallet, etc.) quickly.
1) If they check a bag (it's probably free if they're in F, but just verify that as I'm not familiar with AA's bag policies), make sure anything they will need immediately is in their carryon (and hopefully they don't need anything on the no-carryon list).
2) They will need to show their ID at the check-in counter and at security. They will also need to show their boarding pass at the security line. Have these items ready.
3) Put jewelry, wallet, phone, etc. in purse/backpack (nothing in clothing pockets) to not have to deal with the small trays at the security checkpoint.
4) Follow signage to gate, and keep an eye on the departure boards. Gate changes may occur before departure time, so if their posted boarding time (which is typically 30-45 minutes before departure time) comes and no announcements are made, check to see if there has been a change.
5) They don't get lounge access with a domestic F ticket. There's no point in trying to talk their way in for free. If they pay the one-time pass fee to get in (or if they have access to another lounge through a credit card or whatever), there will *not* be flight announcements from the lounge. It's up to them to make it to the gate before boarding.
1) Larger carryon overhead, smaller carryon under the seat in front of them.
2) In F, meals and drinks are complimentary.
3) Know how to set the phone to airplane mode, and do so. Phones and tablets are allowed (in airplane mode) at all times. If they have a laptop, it's only allowed above (IIRC) 10,000 feet. Basically, listen for announcements.
4) Download the airline app beforehand. I think some AA flights use wi-fi based entertainment, which probably requires the app to be installed (I know United does). You'd have to pay for airline wi-fi to download the app, but wi-fi based entertainment through the app is free.
5) The pilots will typically make an announcement when they start their descent. While they generally don't explicitly say so, this is the "last call" for restroom use until the plane arrives at the gate. Plan accordingly.