Put the two end posts up and then use the first(top) wire or a string to line up the holes of the rest of the posts. I put them 4 paces apart. Horses get horse fencing or barless wire. Cattle, goats, sheep get a barbed fort. Deer get horse or orchard fencing.

Ok, you want to build a fence to keep your horses, dogs, kids in. With horses the fence needs to be within a horse neck of the road. They have a tendency to lay the fence over if there's a lot of feed along the roadside and they can't reach it. You will not have to mow. People will not have room to park there and ignite the weeds with their exhaust. If you have dogs and kids you can pull it back a little but the parking in weeds is still a problem and you'll need to mow or weed eat along it so make it easy to access. Fence goes up once, mowing happens every year. Also every bend has to be braced, you have to build straight lines. If you have a map of the parcel or lot, the fence gets drawn in with a ruler, not free hand or with a compass. 

Be careful not to move the string as you put your posts in. Height doesn't matter at first, I use chin height against the tamp. When you clip your top wire you can tamp down the ones that are way too high.

Again, string the top wire first, use it to even the top of each post by clipping the wire on the low posts first then lowering the other posts and clipping the wire on them last.

Dig your corner posts first and tamp in your post well. Either draw a tight string or your first wire from post to post so you can use the post tamp or water tool(described on first page) to put the posts in. I usually walk the line dropping posts every four paces next to the wire or string, then follow back and put them in.

If you buy one of these monsters, post tamps, buy the heaviest one you can lift. 

This is close to bending the fence and not the post.

Either drive a stake into the ground a few feet and slide the roll of wire over it. A couple of pieces of 1X1 foot plywood with center holes placed under the roll can help the roll spin.

Ok, corners need bracing. Long runs(hundreds of feet) need bracing.    On the corner braces I usually lay my boards next to the corner post to determine where to dig the second hole. If you only have 8 foot boards, one needs to be at an angle so the posts are only about 7 feet apart. The longer the run, the longer the braces.

Stiles  can be used instead of gates where you walk regularly. Basically build them so you can walk sideways through them, but a cow or horse can't. Ponies are a different story, they can get through stuff I had trouble getting through.