I break from the string about 6-8 inches to the right of center. I aim for the center of the head ball as I'm viewing it (as opposed to the center of the ball veiwed dead on, center table). I try to make absolutely sure I'm stroking center cue ball. I follow through keeping the tip in as stright a line as I can and throwing my whole upper body behind it.
Typically, with a nice tight rack I get a good spread and make at least one ball.
I'm 6'1" about 250 lbs so for me getting my technique down is more important than trying to generate a lot of power. For the longest time I couldn't understand why my breaks weren't getting good spreads. Then I started to really pay attention to my mechanics and I noticed some glaring faults.
Firstly, I wasn't aiming right. I was aiming for the point of the head ball that lies on the center of the table. Wrong. If I'm breaking off to the side a bit, I needed to adjust my aim point. This will keep the cue balls kenetic energy from being wasted as it flys off to the oposite side of the table (which was happening a lot).
Secondly, I could see lines on the felt where my break cues tip was running allong it's surface and they were curving to the left after impact. That told me that my stroke was not straight and I was again losing power that would have otherwise been transfered to the cue ball and then on to the head ball, not to mention trowing the cue ball off some.
Typically, when I excecute a good break this way, the cue ball will impact the head ball then travel forward towards the head rail. This also usually results in movement of the eight ball, most often towards the far left corner pocket. Sometimes I hit a little lower than center ball and end up with a stop-shot or a little draw back to roughly center table. Either way if a ball gets pocketed, I usually have a decent starter shot (unless I get unlucky and get frozen on a ball).