After the legal boundaries are found, mark where your corners will be for the fence and dig the post holes with a power auger or a post hole digger. The placement of the corner posts are crucial as everything will tie into them.
You can use line of sight to estimate that the posts are set square and parallel. As you build towards them any slight adjustments will be easy to come in on a square fence rail connection.
To be sure I was within legal limits, I measured in 1 foot from my boundary and spray painted an X to mark my spot to start digging with a standard shovel. If using an auger, set it on the center of the X and start digging. If using post hole diggers, rotate around the center of the X to stay on center. Dig your hole 2 – 3 feet deep for a sturdy post. More if in extremely loose soil, less if in very hard soil.
After all holes are dug for the corner posts, add about 2 inches of small gravel to the bottom of the hole. This makes drainage easy to keep the post from rotting. Set your fence posts in the holes. Attach your post level to the fence post. Then pour in about 40 – 60 pound of Quickcrete to fill up the hole around the post to the top of the hole.
You may be confused by the directions on the Quickcrete bag. It will tell you to mix to a consistent mixture. This method is not requried for setting fence posts. If the ground has good moisture, barely any water is needed at all and just dry mix will soak up enough moisture to harden the Quickcrete. If the ground is dry, just pour a little water in occasionally as while you fill the hole with Quickcrete.
Adjust the post until the post level shows level and the posts appear square with opposing corner fence posts. Support the fence post in the proper position by screwing scrap 2×4′s as a prop. Remove these after the Quickcrete dries.
Now you measure the distance between the corner posts and decide how many more posts you need. If you think you may want to add pre-made privacy panels later, find out their width and space the fence posts so that they will match up. If you would rather have your fence posts exactly the same distance apart, find the exact distance that the spans would be and make sure they are less than 8 foot. If you want the easiest method, space them 8 foot on center so that no cutting is required to install the 8 foot fence rails, then only the odd sized space at the end will need cut.
On to the next step – Installing The Fence Rails