The people who get on board last usually find the overhead compartments full. If you enter the plane late and there is little room left in the overhead compartments on the plane you can take out the things you need on your flight and stow your bag in an empty space on your way to your seat.
Adapt to the local time i.e. stay up protection until it is time to go to bed. This can be hard if you arrive early in the morning but try to hang in there. You can usually adapt to the local time zone around 1 hour per day.
Think back to the most beautiful sunset you ever saw. Remember the colors, the way the whole sky seemed to glow as the sun slowly disappeared behind the horizon painting colors in the sparkling water?
Besides being beautiful the sun can also be quite dangerous. Consider protecting yourself with long sleeved shirts, hats etc as well as using sun block. Do not forget your ears and the soles of your feet and remember that the sun is reflected from snow and water so you may end up with sunburns in really weird places (such as on the inside of your nose) If you are beginning to get bald do not forget to apply sun screen to your unprotected areas on the head, especially if snorkelling.
On the plane
Avoid drinking alcohol which makes you dehydrated. If you drink a lot you will wake up and have go to the bathroom.
Get a window seat so that you are not woken up by people needing to use the restroom or stretch their legs. Use earplugs, eyeshades and an inflatable pillow to get some sleep. Take sleeping pills if advisable (check with your physician).
Avoid seats near the toilets which are noisy. Check out sites such as Seat Expert to find out which seats are good on your flight. If you need to use the rest room frequently an aisle seat is better. We prefer window seats in the middle between the rest rooms and the kitchen. You can sometimes choose your seat already when you purchase the ticket or by calling ahead or using Internet check in.
Do a few exercises (you can usually find them in the in-flight magazine) and walk around the aisle a few times.
If you have a large carry-on bag you do not want to store at your feet get on board early so that you can find a place to store the bag.