Whether you carry a purse, backpack, or small carry on bag...take some time to make sure you have what you might need for a long flight.
Any medications you regularly take should be included. You don't need to pack the entire trip's worth, just enough to get you through the flight. One or two extra would be a good idea as well.
A scarf or shawl would be handy on a long flight, too. Lip balm, lotion, contacts solution, toothbrush...whatever you absolutely need to make the flight easier.
Your smart phone, tablet, and camera should be in your carry on and not in your checked luggage. If you have long layovers, don't forget your chargers.
So you don't forget anything important, make a list. Save it on your computer and you won't have to try to remember what you took last time.