Not all USPS postal facilities accept passport applications; locate the nearest one to you on the USPS website (see resources). Many post offices also have designated days and times for passport applications, or require you to make an appointment, so it's a good idea to check before you go.
You can download application forms online (see Resources) or pick them up from the post office, though you'll save time by bringing a completed application.
Have your passport photos taken at some postal offices for an additional charge of $15, otherwise you'll have to have them taken elsewhere and bring them with you. Photos taken from photo booths are unacceptable.
Pay a passport acceptance fee to the USPS and a processing fee to the Department of State. USPS accepts most forms of payment; the Department of State accepts cash, money orders, personal/business/cashiers/travelers and treasury checks
When applying or renewing you application, you can pay an additional $60 for the expedited processing service.
After completion of your application, it's best to mail it via Express Mail which allows you to tack your application. This will also ensure your application is delivered overnight, and it's the quickest way to receive your new passport.