Plan ahead. That can't really be emphasized enough. You'll want to begin saving up a few months in advance.
Know exactly where you are going. Count the miles and then allowing for your car's miles per gallon (subtracted by 5) you can figure how many gallons of gas you'll need. Add in an extra 50 miles per day just to be safe.
Look up how much gas costs where you'll be. Add one dollar to all prices to allow for unexpected fluctuations. With the knowledge of gas prices combined with how many gallons your trip will require figure out how much gas is going to cost you. This should lead to you having more than you'll need, which is never a bad thing.
When you're planning the money for the trip, factor in hotel costs of one hundred dollars a night and food of twenty five dollars a day for fast food or twenty dollars a meal for restaurants. Again, this should be more than it'll actually cost, but better safe than sorry. To save money you may try taking food with you, and hitting a grocery store on the way back.
Remember to at least look at hotels that are near or on your chosen path. Whether you reserve or not is up to you, but you'll want an idea where you're staying. Or if you have the equipment, camping can be a fun way to save money.
A few weeks before you go, take your vehicle into your mechanic for a checkup, just to be sure everything is working perfectly. If not you have the next couple weeks to get it all taken care of. Some of the extra money set aside could come in handy here.
If you have the time, consider going to attractions along your route. These could add some great fun and extra memories to your adventure. Also check to see if you have any old friends or online ones you could meet for lunch or dinner, along the way.
Music, especially if you're travelling alone, is a very important key. You could be going through places with no radio stations at all. Don't just bring any CDs, but your favourites, that you can listen to over and over again. Mix discs are also a great way to commemorate your trip.
Lastly, we can't forget safety. Know your driving limits and don't push them. Plan stops for food, stretching, and walking every three to four hours. Set fuel stops so that you never get below a quarter of a tank. Getting gas and taking a short walk every so often could seriously save your life. Plan your hotel stops so that you won't end up too tired before you get to them.