Most lifestyle properties will need fencing. If you're keeping livestock, you'll need fences to keep them in, to manage your grazing pasture, and to keep unwanted animals out. If you're running a horticultural operation or planning to turn your entire property into an animal free zone you'll still need to maintain boundary fencing to keep any wandering stock out.
You can either elect to do this fencing yourself, or use a contractor. There is a great deal of satisfaction to be gained from doing your own fencing, but it isn't as easy as it looks. The best advice I can give anyone is if you've never fenced before - start with some professional help. Get a contractor in, work with them, watch and learn. If your contractor isn't happy for you to participate as an apprentice on your own property - find another one who is. That's how I first learnt to fence 14 years ago.
One way to save money but still feel a sense of accomplishment is to have a contractor drive all the fence posts with tractor & rammer and for you to finish all the wire work - that way you can say "I built that fence"...
Whilst it's good to get it all sorted at once, you don't need to deal with all the fencing in one go. Get any boundary fences sorted out first. Use temporary electric fencing to split paddocks up - to work out what works, then put in permanent fences over a period of time (even years).
If you have the opportunity to set out fencing from scratch - whether it's starting with a completely bare block, or by taking out existing fences - put in central races or lanes to make shifting livestock easier. It lets you graze paddocks in any order that suits the conditions at the time. You won't have to move a mob of animals through more than one paddock to get to another, and you'll find it easier to get animals into pens or yards when you need to.
It's better to run a fence line straight up a hill than around it. Straight up a hill is easier to build for a start. If you're in a winter snow area, fences running up/down a slope will suffer less from snow damage. If you have to cross a slope, put the fence along terracing or more gently sloping areas which will be less prone to sliding snow.
Think carefully about what type or height of fence you put in. Conventional height fences are always a safe bet. The livestock you're running now might not be what you have on the property in future. So putting up 2 foot high fences for the Carpathian Pygmy Cattle you're breeding today might limit you next year when you cross graze them with Ecuadorian Jumping Sheep.
A line of fence is only as good as the strainer assemblies at each end. Those are the bigger posts that the fence is tied off at. Learn how to build a solid and sound strainer assembly and you can fence anything.
Try to avoid putting fences at the bottom of steep slopes; the last few metres of pasture directly above the fence line are inaccessible to grazing stock, the effective fence height is significantly lower on the uphill side of the fence, livestock might get trapped up against the fence, or injured sliding downhill into the fence and land slips can destroy or damage the fence.
It is easier to move cattle uphill than downhill.
Gate placement can make all the difference to your day. In can be difficult to get cattle to go through gates in the middle of a fence line. A gateway in the corner of a paddock is easier to shift stock through, unless it's in to a lane/race that runs back along the fence line away from the gate - some animals may go through the gate and along the lane with other animals staying in the paddock following them from the wrong side of the fence.
Gateways need to be big enough for vehicles and farm machinery to fit through. Hay baling machinery will need more width than most to get through - especially conventional size balers. 14 foot (4.2m) gates are ideal, but 12 foot (3.6m) gates should be considered the minimum in most situations.
Allow enough space in gateways for vehicles to actually turn in to the paddock.
The top of gates should be the same height as or higher than adjoining fences. If stock try to jump anything, they'll be more inclined to try jumping the fence than the gate. It saves on damage to gates.
Fencing can be dangerous. Be careful with wire strainers, and any wire under tension. When handling wire always wear safety eyewear and protective clothing - including suitable gloves and steel capped boots. Cut ends of wire are sharp - always bend the last 100mm or so of wire at the end of a roll back on itself, or stick it into the ground to keep it out of the way. Take extra care around any working machinery, especially tractor mounted post rammers and augers.