When your travel plans don't include a definite return date, buy an open-ended ticket. The flexibility tends to cost more, of course, so be prepared to pay a higher price than you would for a standard, round-trip ticket with a confirmed return date.
Most people book flights online, but you won't be able to buy an open-ended ticket that way. Call the airline you plan to fly and book your outbound flight with a ticket agent. You'll be given instructions on how to use the open-ended ticket. Once you know your return date, you will need to reserve a flight in person or over the phone.
You can also buy a round-trip ticket and change your return flight once you arrive at your destination. On most nonrefundable tickets, you'll have to pay a change fee and an additional price for your new flight.
