Sinking metal fence poles can be a lot of back breaking work. But here are some ideas to make the task much more manageable and easier to perform. Walk your land carefully measuring and marking the locations for your fence posts. Make sure that you are avoiding underground power lines, water lines, or gas lines. Clear the locations of rocks and debris. Once you have marked out your fence with the locations for the posts, take your garden hose and thoroughly soak the ground to soften it for the installations. Next dig pilot holes to mark the exact spots and to make the installation easier. In fact if you dig them before soaking the ground, driving the posts into the ground will be even easier.
Pour quick drying concrete into the pilot hole. Allow it to start setting, place the post into the hole. Make sure it is plumb to the ground before the concrete fully cures. Use a fence post driver to drive the post into the ground. Slide the fence post driver on top of the metal post and make sure the driver is squarely on the top. Place both hands on the handles and raise it about six inches above the top of the post. Pull downward very quickly and repeatedly until the post is actually driven into the ground. Make sure to wear well insulated gloves while using the driver or the vibrations will hurt your hands. Also make sure not to pull the driver up high enough to where it may slip off the fence. It is heavy and can injure you if it falls. Use a level to check to make sure the post is plumb once it is in but before the concrete completely cures. Make any adjustments. This is critical because if your posts are out of plumb, the fence will flex and damage the brackets holding the panels to the post. If this happens you will have to replace the posts and the attached fencing as well.