I flew to Turkey with my daughter at 15 months—that's an eleven
hour flight! This is what I did:
1) Buy a couple of new toys or books that he/she has never seen and
then bring them out when he/she starts to get bored.
2) Give a bottle at take-off and landing to help with the ear
pressure.
3) Snacks
4) Depending on the time of the flight, maybe hold off on giving a
nap until on the plane.
5) Don't worry if you have to walk up and down the aisles if it
means your child won't cry. People care less about a walking child
than they do about a crying child.
6) Don't worry about the people on the plane. There is enough
stress with them adding to it.
7) Stay calm and relaxed, even happy. Children definitely sense our
stress and will feed off of it. Tell yourself it is going to a
pleasant flight, and try to believe it. Trust me—this is seriously
important.
I hope this helps!