When we met with the Pastor who would be officiating, she provided us with three or four programs from weddings she had done in the past. All of them were pretty much the same layout with the processional, welcome/intro from the Pastor, 1st reading, unity candle (optional), 2nd reading, abbreviated sermon, vows (traditional), recessional.
Of course, it will vary depending on religion but ours was fairly non-denominational. We just decided on which readings we wanted, whether or not to write our own vows and what songs we wanted our quartet to play at specific points of the ceremony. It was a lot less daunting once we met with her, so if you have an officiant already it might be a good idea to reach out to them to discuss the flow of the ceremony so you know what decisions you will have to make.