There's lots of good advice here, and I will probably end up overlapping it a bit, but here's my tuppence worth:
We buy it reasonably early in December to get a good tree. But stand it in a bucket of water in the back garden for a week or so to get a good drink and keep it cool for longer. (And a chance for any creepy crawlies to crawl off!!). If we have had it in a "stocking net" covering to transport it, we take that off as soon as we get home, to let the branches spring back out again and fall into a lovely tree shape.
On a weekend day, around a week-10 days before Christmas, we will saw a couple of inches off the base of the trunk, to let freshly opened bark drink better indoors. (Trees drink by sucking water up through their bark not the trunk itself). And do any other tidying up needed (like more trunk gone if it's too tall, or taking a couple of inches off the top stem, or any absolutely necessary clipping of branches - but generally we don't trim the branches, just worry that it won't hit the ceiling).
We then put the stand on the trunk outdoors. We have an American dish stand - which screws into the trunk to keep it solid, but has a bowl underneath that holds a good drink of water. (Water comes later once indoors).
Then we open the doors wide, bring the tree in base first, and get it settled in place. Once we have decided which way to turn it, we fill the watering bowl with tepid water (not freezing cold - to try and avoid shocking it too much) and let it settle in the room for an hour or so while we all warm up again.
Then we decorate it as normal, and the only difference to fake tree years is that we have to fill the bowl with water every day (or maybe 2 - but they tend to be thirsty and the more you keep it watered, the better the chance of keeping the needles).