One thing that didn't come to be obviously when first starting out as a new road cyclist, was the importance of keeping your hands loose, and your arms bent, when out on the bike.
Like most other new road cyclists, I had a vice like grip of the bars and straight arms when riding. For a number of reasons, this isn't great. It puts tension into your arms and shoulders, you feel every bump on the road (and as we all know UK roads are in a poor state at the minute) and you don't isolate your legs. I came back from many a ride with shoulder ache tension and headed straight for the ibuprofen!
When you watch the pro's, either on the road or track, you'll see that they always keep their arms bent and it's one of those simple things that isn't obvious to you as a new road cyclist. You just jump on your new bike and turn the pedals.
To give you some idea as to how tight your grip should be, I'd like to give the example of a horse rider. Horse riders gently hold the reins in their hands, they don't hang on to them, like horse handlebars. They use balance and leg strength to stay on the horse, the reins are there for other reasons. Same with your bike. Keep your grip on the bars loose and relaxed and your arms bent at the elbow, whether sitting up, or down on the drops. When you do this, you feel your legs more.
The best way to demonstrate the point/sensation I found is to ride up a hill. Sit up on the bars and then totally relax your grip, almost as if you aren't even holding the bars, bend your arms like a time trial rider. What you'll suddenly experience is how much you suddenly focus on your legs and what they're doing. If you can repeat this when you ride on the flats, it will make you a better road rider.
If you have a quick look at this Youtube video from 1988, it will show you what I mean.