Whether you use a real tree or an artificial one, you can't put it up alone. First, it needs to be inspected to be sure you're not tracking any prey in with it. (It is an outside thing inside, after all.)

Once the tree's been fully inspected from its prone position, it's safe to place the tree upright. Before you add lights to it, you should always remember to check the stability of the base.
The lights go on next. Be sure each section of cord is attached securely to the tree.
Oh no, I forgot to check if all the lights worked before putting them on.
Next, lay out your ornaments so they're easy to reach.
The fun part, of course, is putting the ornaments on. Don't let them fall!

Once the tree is covered in ornaments, you can add the tree-topper. (This one is named "Hey, get offa there.")

Once it gets dark out, you can turn the lights off, turn the tree on and enjoy!
Of course, you'll have to wrap presents to put under the tree as well. Good luck with that.