I would concentrate on getting more lag in my swing. That is a big part of creating the kind of speed you need at impact to hit crisper shots. Proper lag ensures that the club head is accelerating at impact. Here is a link where someone explains lag.
Slow down...I find I create more lag, and therefore better contact, if I let gravity begin my swing and accelerate about a foot or so from the ball. Do I always do that? No...I still have that impluse to hit from the top, and while I know I lose power and control, I still do it. Duh...
Do yourself a favor, and buy a Swing Speed Radar/Tempo Timer. Once you have it swing your driver and see what speed you get, Then, try a few things that you have read or heard about and see what works for you. I did this exact thing and I went from 95 PMH to 105 MOH in a few weeks. Wednesday I got over 110 a dozen times, with a high of 115 MPH. Some of the gain came from doing the fundermentality correct things in my swing. The last 10 MPH came from my own ideas, and now I have to work on making those ideas work all the time and see if I can get my average up closer to where my max of 115 is. Time will tell if I can do it or not. Bottom line is this. If you don't buy the Swing Speed Radar you will never figure it out. You need the radar to tell you exaxtly what works and what doesn't . There site is Sports Sensors, Inc--Overview, and please tell them Don Fisher told you about their product and recommended you get one. And before you ask, NO, I don't work for them, I just use their products.
I will second the Swing Speed Radar. Absolutely essential if you want to increase clubhead speed. Because you'll never really know what is working unless you've got a good consistant gauge. They may be less than $100, but they are accurate (as much as some of the launch monitors, and more than some too), and they are really consistant.
Another thing is to find the imaging of the swing that works for you. Its easy to say "hold the wrist cock for as long as possible". But for some people (like me) you need to put it into words that can make sense in a simple swing thought. What works for me is to not focus on holding the wrists, but to do everything else correctly and add the concept of "start the downswing with the legs & hips before the hands are finished with the backswing". This way, my body is moving so fast and my hands are trying to "catch up" with whats going on that they have to release late because the rest of my body is at impact position before I know it. I tried every other visualization for body movement to hold my wrists but to no avail.
Point is, if you don't find something, keep examining what the body has to do during the swing to get the speed up. Then make up your own phrasing to use as a swing thought. People respond to language that way, you can pretty much say the exact same thing to a person, but because you used a different 'saying' or figure of speech, it make all the difference.
I've got the speed stick and it does help and gives you a reference but the length of it hinders you practicing the same swing as you might use with a driver. I had tightened up my swing so much for control that I was swinging around 85 mph on the speed stick when I got it and now I can max it to 115. I plan on working more with it but my drives have went from 240-260 with roll to over 290 with roll and the occational 300+ a couple of times during a round and getting longer it seems with every trip to the course. I can still get the occational 200 yd drive when I don't square the face correctly or make a mishit on the face but the speed is definitely up and I feel the speed stick helped me know that.