How tall are your posts before driving them in? Being 5'7", and driving my 6 1/2ft posts, I have to stand up on something. If I am not up with the post top, it always goes in crooked because I am pulling it.

Not sure how many posts you have, but sometimes using a sledge hammer or a newer driver can help. My friend just got a spring-loaded post driver, and says it is MUCH easier to use than just a weighted driver. Haven't tried her driver yet, so have no opinion yet.

In extremely hard ground, I have found using the sledge hammer to be easier. My hands just can't take the slamming down of the driver handles. Again, I need to be higher up, to make this work. So I stand on the truck tailgate or my plastic, 2-step stool to gain the needed height to drive in the posts.

If the ground is hard, mark out where your posts will go. Scrape a small hollow in the dirt, and fill that hollow with water a couple of times a day for a few days.

A little water will soften that dirt right up.

The quality of T-posts keeps going down, and the poorly made ones are difficult to get pounded in straight.

It helps a lot to get up above the post.

for a driver, I use an iron pipe. a 2 1/2 inch well stringers pipe works great. Weld a top on it and 2 handles on either side. Lift the pipe and drop it. Much easier to control. Be sure it's long enough so that you don't over lift it and have it come down and mash your finger between the handle and the post.

Thanks to all! I hadn't thought of getting above the top of the post to drive them. I'll give that a try.
--Steve