That is not necessary. Upon completing your booking, you will receive an e-mail with your flight confirmation. If you have to stop by the check-in desk in order to obtain your boarding pass, print out the confirmation in order to present it to the check-in agent. However, you can check-in online via the web and print out your boarding pass at home, at no cost.
In any case, remember to bring the documentation necessary for your flight, which will vary depending on your nationality and origin and/or destination of your flights.