Most university ag websites have a section on how to properly measure and run barbed wire fence. The University of Georgia has a good one.
There are as many ways to run fence as there are people who do it. I've run lots and lots of it and here are some of the things I have found out over the years.
1. ALWAYS brace the corners and put in braced stretching posts in long runs or changes in elevation.
2. Always start with the bottom wire. I know some people start at the top and work down but for safety reasons don't do it. If you start at the top, as you work your way down, your face, shoulder and arms are always close to the wire you have already strung and sooner or later, it's going to bite you. It also makes it easier to clip the wire to the T-posts as you are not working through the already strung wire.
3. Never use a tractor & FEL as your only means of tightening the wire. Sooner or later you're going to overstretch and break it and you better be ready to duck and pray. I attach a come-along to the FEL and the wire to the come-along. I use the tractor to take the initial slack out of the wire and position it at the required height and finish tightening it with the come-along.
4. I beat the first T-post in until there is 44" of stick-up for 4 strand. (It'll vary depending on whether you are running 4, 5 or 6 strand fence) I usually mark a stick at the height of the top of the T-post driver when the first post is at 44". That way you only have to measure once. You just beat the rest of the posts in to the mark on the stick and they will all be at 44".
5. Use either the bottom wire or a string stretched between the brace posts as your straight line for driving the T-posts.
6. I start my bottom wire 12" above the ground and subsequent wires 10" apart. That leaves 2" of T-post above the top wire for a 4 strand fence. For a 5 strand fence beat the posts in to 44", put the bottom wire 10" above the ground and subsequent wires 8" apart.
7. Never be tempted to run barbed wire around a corner post and keep on going. You might be able to do that with high tensile, barbless wire but not barbed wire. You'll never get it stretched properly because the barbs hang up on the corner post and it'll come back to haunt you.
If you use properly brace corner posts and braced stretching posts you won't have to worry about them twisting and the wire slacking off. Properly braced corner posts and stretching posts are the foundation of your whole fence, don't skimp. It's better to take the time to do it correctly once rather than having to go back and redo it again and again.
I really recommend that you check out the U of G website on how to run fence. The description and diagrams will explain it all. Hope this has helped.
