What I take on board
I use a backpack as a cabin bag as I like to be able to have my hands and arms free. It's just easier to carry things around attached to your back!
When replacing old backpacks I look for ones that have different compartments and pockets. It makes life a lot easier when you need to search for something! Side pockets are for water bottles, tissues and hand sanitiser. Front pocket for pens, paper, phone, keys.
My basic items are pictured, the only thing that gets me through long flights is reading material so I have a variety on me! Magazine with actual long articles not just pictures! iPad loaded up with at least 5 novels ( I read a lot!) plus at least one hardcopy book. Days gone by I would pack a small library in my suitcase as I went off on an extended trip, and I would leave a trail of books behind me. If I really loved a particular book and couldn't bear to part with it, I would post it back to Australia! I'm sure European postal services all had a dramatic drop in their profits with the arrival of my first iPad! But I do still manage to carry around a hardcopy, just for when the battery life in my iPad is low, (panic stations if it's a good book!) or when reading outside in bright sunshine, I find it difficult to read an ebook in bright light. So lying by the pool always involves having a 'real' book.
I always pack a cardigan, even if it's boiling hot as I'm getting on or off the plane. Inside the air-conditioning is perennially at Siberia levels and I freeze. Not pictured but I also have a change of clothes as I've had 4 occasions where my baggage hasn't arrived the same time as I have! One time I was stuck in the same clothes for 2 days (getting smellier as the days wore on!) Shoes too, if I'm going from summer in Europe to winter in Australia.
Finally toiletries bag with assortment of toiletries for life on board the plane and later, incase your baggage ends up in different country to the one you've arrived in!
In the past few years with the availability of free wifi I've also started travelling with my laptop, a lightweight one that fits in my backpack. That also means my carryon luggage has a collection of chargers to charge up all the electronics that now travel with me!