This site,
Tricks of the Trade, is an excellent resource for helpful hints in various professions given by those in the said profession. Flip through the archives to read short descriptions of all these trade secrets. My favorite, thus far, is for frequent fliers: "When all that is left are the middle seats on the plane, ask the person at the counter if you can be seated between two people with the same last name.
Typically they will be family members travelling together and hoping to claim the whole row. If you split them up they will offer you a trade, and you'll wind up by the window or on the aisle."