I'm sure you already know about how hard it is to find good help, especially in this day and age. There will come a time when you can't do something yourself. One thing I know that many people should not do themselves is garage door installation. I suggest leaving it to the pros.
A good company can easily come to your place, assess the garage, remove the old door, and put up the new one in almost no time flat. They do hundreds of doors a year so I would trust them to handle my door. They can also be more affordable than having to learn the hard way that you shouldn't install it yourself.
I like saving money when I can. There are times, though, when it's smarter to pay for services than to have to pay more for doing it yourself. I know that these services can take care of that for me.