Brace posts should be 5 feet from the corner post. The brace posts and all other posts should be set to the same height as the corner post.

When setting the corner post, make sure it is straight and level. With a creosote post the surface is usually uneven. So using a carpenter's level may actually be less accurate than standing 10 to 15 feet from the post and using your eyes to adjust its level.

Keep in mind that the fence wire will be attached to the posts on the inside of the run posts but on the outside of the corner and brace posts. Attaching the fence on the inside of the run posts prevents animals from pushing on the fence and loosening the fasteners. Attaching the fence to the outside of the corner and brace posts allows the fence to be stretched tighter.

To make sure your posts are in the correct alignment, stretch braided nylon twine from the top center of your corner post to the end post. Set your brace posts in line with your corner post. Set your run posts to the outside of the center line marked by your layout string. Nylon twine is best because it can be stretched tight, creating a straighter run line.

The corner and brace posts should be set in the ground with concrete. Pour an 80-pound bag of fast-setting concrete, such as Quikrete, into the hole. Tamp the mix into the hole, then add water. If the ground is wet, let the concrete absorb the surrounding moisture. Let the posts set up for at least two days. Let them stand longer if the weather is wet.

Install cross posts horizontally between the corner and brace, forming an "H." Cross posts can be made from run posts. They are typically 3 to 4 inches in diameter. For the first cross post, measure down 7 inches from the top of both the brace post and the corner post. Make a 1-inch, horizontal cut using a hand saw. Measure down the diameter of your cross post (3 to 4 inches) and make another 1-inch cut. Use a wood chisel and hammer to remove the wood between the cuts. For the second cross post, measure down 17 inches and make the same cuts. The flat cutouts support the cross post. Measure the length of the cross post, making sure to add length for the cutout notches in the corner and brace posts. Cut the cross post to fit snugly between the corner and brace posts. Hammer a 10-inch spiral landscape spike through the corner and brace posts into the ends of the cross post. You can drill pilot holes, but posts set firmly in concrete will stand up to the hammering.

Complete your corner post by using single-strand, high-tensile (17,000-psi break load) wire to further strengthen your corner post brace. This wire is commonly used to make electric fences, as is the ratchet strainer used to put tension on the wire. Cut a piece of wire long enough to make a loop going from the top of the brace post and around the bottom of the corner post, with 6 to 8 inches extra. Loop the wire in a figure-8 pattern. Position the strainer near the inside top of the brace post. The figure-8 loop allows tension to be applied equally to the entire wire.