Here is some great advice from the folks at Lonely Planet for planning that big trip.
Planning might sound boring but once you start buying guidebooks, imagining your itinerary and working out where to go, you’ll feel like you’re actually doing it.
Paperwork is important to avoid the horrors that you hear about travelers sent home because they didn’t have the right visa or their passport expired. Passports are your proof of nationality and act as your main form of ID overseas. For example, It is a requirement in Japan to carry your passport with you at all times. Your passport should have all your visas and entry stamps showing you have a legal right to be in a country. Remember that every country could potentially require a visa. It is best to check and the best place is usually the embassy site of your destination. A good portal to many of these is Project Visa www.projectvisa.com
Money and Costs
Start saving straight away as saving money will let you travel longer and enjoy the trip. The best way is to use a budget as a guide and give yourself a bit of room to enjoy your trip. Good budgets allow for new possibilities and give you the chance to enjoy the odd bit of serendipity.
Health and Safety
Before purchasing that all important ticket you should feel that your destination is safe. Research the destination and ask yourself are you OK with the level of risk. Once you book your ticket start to think about your pre-departure medical plans. At least 6 weeks before you go you’ll need to begin immunisations. Think also about bringing a medical kit even if you are going somewhere safe. It will come in handy for those unexpected colds and even hangovers.
Travelling light is usually the best policy.
Make sure everything is organised before departure day. Check airline website for what you can and can’t take on the plane and confirm your flight.