The question is: how?
The good news is that there are multiple things you can do to take the guesswork out of the equation.
The most pivotal steps are these:
First, if you're not already plugged into the best online recruiting platforms, that should be your first stop. This is far and away superior to placing an ad in your local paper or other more traditional means of hiring.
It isn't that you can't find plenty of good people in most any good-sized city, but you gain access to a much broader and deeper pool of talent if you shop globally for your new hires.
In the old days, that usually meant paying a premium to try and get a new hire to relocate. However, managers are increasingly embracing the notion of letting many of their staff members work from home, wherever that might be. If you're willing to do that, you can find top talent anywhere in the world and put them to work for you in short order.
Second, you'll want to hold at least three interviews. One should be over the phone to get a general sense of the employee. Next would be a second interview where you introduce the prospective new hire to the people they'll actually be working with to ensure that he or she is a good fit. Finally as a last step, do a written or practical interview that serves the same function as a university exam.
This last bit is key, because it gives you a chance to see how they work and how they think. That can generally tell you how efficient and effective they'll be in the position you have in mind for them.
If you do all of these things every time you hire, you'll almost never mis-step when bringing a new employee onboard.