Watch the longest hitters on the PGA Tour and what do you see? Players like Tiger Woods, Bubba Watson, Vijay Singh and J.D. Holmes all hit their driver as hard as they can. Why? Because today's big headed drivers have sweet spots larger than the golf ball itself, so you can swing for the fences and still hit it solid.
To hit your driver as far as possible, swing longer and faster, letting yourself release the golf club through impact. Worry about control issues later.
Tee it high and play it forward
Today's drivers are 45 inches long, so the optimum ball position is forward (off your left toe, for right-handed golfers). Tee the golf ball high so you'll catch it on the upswing for a longer carry and roll - the best of both worlds.
Trajectory: high launch, low spin
Through a combination of finding the right driver and hitting the ball more on the upswing, you will begin to launch the ball much higher. This will improve the final one-third of your ball flight, creating longer drives, with no loss of accuracy. When you hit your driver on the range, watch how the ball behaves toward the end of its flight. If you notice it's falling abruptly from its peak, test a driver that launches it higher with less spin.
Tip: Find a good lie on the tee
Most tee boxes are imperfect: They slope in one direction or another, have divots, etc. Tee up in a place where your feet are even and level, even if this means teeing up right next to one of the markers or moving back a club-length or two.
Another tip is to make sure you tee up on the same side of the tee box as where the trouble is. So, if there is water or out-of-bounds on the left, tee up on the left side of the box. If there is trouble on the right, tee off on the right. This will allow you to hit away from the trouble instead of hitting at the trouble.
Test-drive some drivers
The great thing about golf today is most golf courses have "demo" drivers you can test. Also, most golf equipment companies have "demo days" where they have sales reps who furnish "demo" clubs for consumers to test. Whenever you can, take advantage of these opportunities. I know from experience that testing will help you find the perfect driver, the one that magically produces more yards.
Tip: Know your driving days
When you go to the range before a round, you're never sure what your shot shape will be: could be a slice, draw or a straight shot. Every day is slightly different. If you want to avoid "bad driving days," where you hit the ball all over the place, pay closer attention to what you showed on the range.
On the course, plan and execute your tee shots based on your tendencies that day. Your misses will be more manageable, and you'll avoid a lot of stress. You'll at least be able to get the ball around the golf course.