Taking out the Jam

Another use for the reciprocating saw is to run it down between the jam and the rough opening. This is sometimes needful if there is a stubborn screw or nail that is holding, but you can't get it removed. If there is any trim or brick moulding around the front of the jam, you can use your prybar and pop it off.

Threshold

Most of the time, the threshold will come up with the jam sides. If not, just slip your bar under the threshold and pry it up. If you cut the side jams in two, be careful that the top doesn't fall down on your head while your yanking the lower pieces.

Cleanup and Prep Work

Set all your old material well out of the way until it can be hauled off, or moved to another location. Make sure you remove any remnants of nails or screws. If there was any caulk used on the threshold, scrap it all off. It's best if the rough opening is as clean as possible.
Vaccum up any debris. Then measure the rough opening to verify that it is the correct size for the new jab. Measure width and height.
In most cases you'll be leaving the new door in the jam during initial installation. This makes it easier to get a plumb, square jam.