Take an extended test drive. Don't just take it for a quick spin through the neighborhood by yourself. Instead, enlist everyone who will be regularly riding in the car to share their opinions. Ask the dealer for a full afternoon test drive so that you have the chance to take it on the freeway to check things like the pickup and the blind spots, and spend some time really feeling the comfort of the interior.
If you aren't concerned about getting the absolutely latest model, consider car shopping in November or December. During this time frame, dealerships will offer deals on the current models. They want to clear out their inventory to make way for shipments of the next year's models. This means that you will be offered more incentives, lower sticker prices, and more room to negotiate!
Bring a spare set of keys with you to the dealership. When they ask for the keys to your trade in, give them the spare. Some dealerships will use your car keys to hold you hostage if a deal is not made. You want to avoid this, so make sure you have the ability to walk out of the dealership at any time without having to ask for your keys.