You have picked the perfect door, one with great curb appeal. While that is great, the main function of your new entry door is sealing the inside from outside air, rain and snow. If done improperly you will have wind and water leakage into the house, and possibly even rotting of the surrounding framing of the door.
The initial step of any exterior door installation is to get the sill
perfectly level. If the sill is not level it will be nearly impossible to get the door square with the jamb. Installing some sill protection is a step that got easier with the introduction of sill guards and sill tapes. Covering the floor where the door sits with one of these products will keep out and shed water to the outside. There are many on the market, just pick one that fits your installation best. Caulking the floor and setting the door is no longer an acceptable installation practice. Caulking breaks down over time, and you will be left with a vulnerable point of water entry.
Always install house wrap
when possible. This is a great water and wind barrier. Cut the wrap to fit inside the opening at the sides. Cut the house wrap at the top of the door on small 45 degree angle. Tape it up out of the way so it is just above the exterior of the door. Always caulk the perimeter of the rough opening behind the brickmoulding or nailing flange prior to setting the door.
Be sure to slide drip cap under the house wrap. Caulk and tape the angle cuts to keep water from penetrating there. A place that often gets overlooked is the jamb and sill connection. Be sure to caulk this area, water runs down the door jamb and collects at the sill. Caulking here will not only increase the life of the jambs, but helps the jambs from rotting. Finish caulking where the brickmoulding meets the jamb. Caulking also adds to the energy efficiency of the door.