You maybe subjected to a short body search. On international flights check out your duty tree allowances. Do not take more unless you are prepared to pay duty. Remember that smoking is not permitted on planes on most domestic flights and is forbidden in some terminals. You can fly at greatly reduced rates by delivering a package as an air courier.
Some companies advertise for freelance couriers in newspapers or magazines.
You can also check the Yellow Pages under Courier services although some listed companies don't use freelancers. Even if you don't fly regularly, consider joining a frequent flyer program. Some credit cards award a points system for 'air miles' traveled, which entitles you to free travel after you have accumulated a certain number of points. However, membership of this system is not automatic and has to be requested by the cardholder. Whenever I am trying to find out how to do something.