Visit United.com and click on the "Join Mileage Plus" link located about midway down the page on the right. Fill out the form on the next page. Select "Enroll" to join Mileage Plus.
Travel on United or United Express flights. When you book your flight, enter your Mileage Plus number. You'll automatically receive award miles.
Fly with airline partners of United. Most flights with United's partners will credit you with miles, but you'll want to check with the airline before booking to be sure. Visit United Airlines' Partners page for a list of partner airlines.
Rent a car, reserve a hotel or book a vacation through one of United Airlines' partners. See Reference 2 for a list of partnered companies.
Use a United Mileage Plus debit or credit card. For every dollar you spend on your debit or credit card, you'll earn miles. You'll earn extra points for using your card at retail, dining, finance and other partners. To apply for a card, visit United Airlines' United Mileage Plus payment cards page. Choose the card you'd like. Fill out the application information.
Purchase miles by selecting "Buy miles" on United Airlines' "My Award Miles" page. This can get a bit expensive unless you're only purchasing a small amount.
