If your four-legged family member isn't used to traveling in the car, or doesn't do it frequently, it's a good idea to have a few short car rides leading up to the big travel event so he/she will be more accustomed to the experience. Of course, make sure the car is kept at a comfortable and well-ventilated temperature for everyone's sake!
If you are traveling by air, check with each individual airline regarding requirements for traveling with pets well in advance to make sure you comply with the rules and have everything you need. Most airlines even offer the option for in-cabin travel, but only for one pet per cabin.
Following these tips should ensure as pleasant as possible trip for two legged and four legged family members alike!