Travel Tips

You should always book a flight directly through the carrier whenever possible. Carriers have generally started offering discount fares for select flights at select times that are less expensive than travel sites like Orbitz and Expedia. Use these travel sites to get an idea of your options and the general price you should expect.
You should start checking out fares about three months in advance and then continue to watch them to see when they go down. When they go down and how much they go down depends on how many seats are available, what sort of specials the airlines running and how popular or competitive the route you're trying to book is.
You should book at least a month in advance. When less than a month remains, fares usually rise. When you cross the two week boundary, fares go up much more.
Southwest doesn't show up on travel sites like Orbitz and Expedia. You can download a desktop (i.e. - works on its own, instead of through a browser) application called "Ding" which will notify you of sale fares often not available on their web site.

Cancellation policies vary among airlines and the class and fare you chose when you purchased the ticket. For instance, Continental offers a 24-hour grace period from when you purchase the ticket, where you can cancel your reservation for no fee, or even change it for free, provided the new fare is not higher.
Southwest allows changes for free, provided the new fare is not higher. You can also cancel, but, instead of a refund, you will receive a credit which must be used within a year.
If you must change a flight because of health reasons or catastrophic events, most airlines will waive the penalty associated with the change, but will still charge you the difference in the new fare.

When you actually pick up your car

In the US, if you're under 21, you generally cannot rent a car. If you're under 25, most companies will allow rentals, but will charge an excessive fee (usually about $40 per day). It's just not that easy.
Not all companies allow unl