If you’re reading this, you obviously have an internet connection. Which means you have a wealth of information, literally at your fingertips. Use it. When it comes to planning, the key is to balance having an understanding of where you’re going, with what you want to do and get out of your trip, and being open to surprises, difficulties, and unplanned, impossible-to-foresee opportunities.
Figuring out where you want to go is as sipmle as deciding which places get your blood rushing. Where have you always wanted to go? Always wanted to see Tahiti, or Australia, or Spain? What have you always wanted to do? Hike the Alps, or the Annapurna circuit, or dive the Great Barrier Reef? Start with questions like these.
Do some research, both online and in print guidebooks. Use the Internet, your local library and your bookstore; that’s what they’re there for.
Don’t overplan though. If you know things you want to do and places you want to see, great, obviously try to plan them but be open. Some places don’t conform to schedules (ask anyone who’s taken a train in India), and in general you want to try to be open to sudden opportunities. They will arise, unexpected; a local will take you under their wing, a traveler will have similar plans.
Keep your wits about you, of course, and judge situations are prudently as you feel necessary. But at the end of the day, get out there and have fun, no matter your plans. Do what you want to do, wherever you want to do it. And be ready for what comes up time and again, the travelers we talk with say the best things on their trip, were all unplanned.