Here is my steel corner post. 3 inch steel angle iron 3 feet in the ground set in concrete. This is the most common type of corner post around here. You can buy at any good fence company or feed store. I also have some wood corners but I prefer these as they will be there untill some one pulls it out. I have built about a mile and half of four strand fence in the last 3 months. I put my roll of wire on a pipe and put it in my bucket i can then pull it off as I walk or just back the tractor up and let it spool off. You need a good fence tool. That is a single tool that is a hammer, pliers, cutter, staple puller, wire twister. I strech the wire with my BX. I clamp the wire to the bucket with a pair of vice grips and then slowly back the BX up. You got to be careful are you will pull down the corner post.