In the Store: Unlike mountain bikes, road bikes can last forever. Which means you'll probably want to upgrade before you need to, so get the nicest bike you can afford. » Consider your budget and performance needs in terms of components. Nearly every bike is offered with various levels of componentry, dramatically changing the price. Remember: Upgrading everything à la carte will cost you a lot more than if you pony up for the better stuff initially. » Ride it before you buy it. At the very least, try a couple of sprints and hard corners in the parking lot.
In the Field: Before you head out, check to make sure your fork's quick-release levers are tight, and, if it's been a few days since your last ride, top your tires off with some more air. » Be a good Boy Scout: Never leave home without a spare tube, tire levers, pump, and multitool.
At Home: A little bit of love goes a long way. Keeping your chain lubed and your derailleur free of grime will keep your bike out of the shop longer.