First off, we kind of need to know what you are trying to keep for livestock.
A hog fence doesn't need to be real tall, but it has to go BELOW ground level since hogs root under fences,
And it has to be STOUT! Hogs are like horses and they will push on fences like crazy!
Horses don't need fences that go all the way to the ground,
A good thing to keep them from rusting out and when you need to mow under them!
Horses need TALL fences, and they like to push on the fences, so you will have to build stout, or use electric or barbed wire topper.
Cattle won't push on fences like hogs or horses, but they like to stick heads over the top and try to eat from the other side, so they will mash fences.
Again, a barbed wire or electric topper is a good idea.
If you breed, you will need a weave of some kind on the bottom of that fence.
Small live stock will get out regularly if you use strands instead of woven fencing...
Chickens, turkeys, rabbits, ect. will need a very fine weave fence that is all the way to the ground and about 3' or 4' tall.
Goats & Sheep will need a HEAVY Wire fence.
Goats and sheep (Especially goats) will chew on everything, including the fence, and they can gnaw their way through if you use light duty weave.
Again, if you intend to breed, you will need a fairly small weave closer to the ground to keep the small ones in!
'T' post fences,
Looks like a piece of 2" metal tube about 2' long with smaller tubing on both sides for handles.
Sure beats trying to drive them with a sledge hammer!
We used everything from a 'Hi Lift' jack to vehicles to stretch the fence.
('Hi-Lift' is a brand name for what is commonly called a 'Farm Jack')
No matter what kind of fence you put up, you will need STRONG corner posts!
That means digging and setting large wood, concrete or whatever posts.
You will also have to set a 'Heavy' post if you angle your fence up or down steeply, since the angle pulling on the fence will change and you may have to put the fence up in sections.
Heavy post every time you 'Stop/Start' a different angle of fence.
Stretching Wire. FENCE ALWAYS GOES ON THE 'INSIDE' OF THE POSTS! so the live stock push it into the post,
If it's on the 'Outside' of the posts, the livestock will just push the wire away from the posts.
Types of fencing...
Welded together wire that makes squares, bottom squares closer together at the bottom to keep little critters in,
Comes on rolls.
This is a single strand of high tensile strength wire.
You put each 'Run' up as needed.
You use a ratchet device to stretch the wire until it's very tight.
Mostly used with wooden posts, but you can use steel posts with it also, just don't let the wire rub directly on the post.
Good for long hared animals that like to stretch out fences trying to scratch themselves or eat from the far side of the fence.
'Scratching' damage can be mitigated if you put up a scratching post... Just a large post with a bunch of spike nails or bolts driven into it with about 3" or so sticking out.
If you have animals that shed, this is a good way for them to scrape off the winter coat without riding down the fences.
That's some, there is a lot more if you get into it...
A trip to the local 'Farm Store' might make things more clear on what type of fences are available for what type of livestock you are wanting to raise...
Does anyone know of a good "How to" link for T-Post Fencing? I want to learn how to put up a t post fence, what materials are needed, etc.
There is no better teacher then experience. Find yourself a neighbor who needs to put up some fence and volunteer to help if they will teach you how to do it.
T-Post is some of the easiest fence to build and only requires a few tools:
1. post driver - hand hed device that lets you drive the post into the ground. Looks like a heavy tube with handles.
2. hammer x 2 - I use trees as part of my fence, in the ozark tradition, and so my fences are not always that straight. Trees make great corner posts and streatcher posts every once in a while. The hammer will let you drive the nails into the trees to hold the barb wire and you can stretch the wire using one hammer while you hammer the U shaped nails with the other.
3. screwdriver - Easiest tool there is to put the post clips on.
Lots of other tools you can get but they are optional. Of course if you want the perfect fence you will need all the optional tools and a lot more time. My fences are designed to keep cattle and horses in but fail when it floods so they can be fixed quickly.
As mentioned, we would need to know what you're trying to keep in (or out).
JeepHammer gave most of what you need to know. A few things I could add.
T-posts come in different grades/qualities. If you're trying to retain anything bigger than a rabbit, don't waste your time with the cheap posts.
For hoofed animals or if you're in a hilly area, consider using no-climb horse fence instead of welded wire. It's stronger, more flexible and designed where they can't get their hoofs in the fence for climbing.
If you want/need something that's esthetically more pleasing, consider split rail or PVC fencing. You could put up these types of fencing then put welded wire on the inside if what you're trying to contain is smaller (e.g. dogs).
For any steel fencing (be it welded wire, no-climb, hi-tensile...), it'll be pretty shiny when you first buy/install it and after putting it up, you may find yourself saying "oh crap, that sticks out waaaayyyy too much". Don't worry. It'll turn gray over time and fade where it doesn't stick out as much.