I'll keep adding to these as I go along
1. Car - I was fortunate enough to purchase a Civic Hybrid shortly before I left for my road trip across 48 states. The money I saved on gas was overwhelming! I actually made it to Texas on 100 bucks!
2. Sleep - Knowing where you're going is just as important as knowing where you'll be staying. I briefly looked at Hostels around the country but since I'm a woman and traveling alone, I decided to choose a chain of hotels. I chose Marriott and signed up for their rewards program. The ease of reserving rooms and canceling when I wanted to change routes was awesome! Everything was saved on their website under my personal account and the points and rewards I received during my road trip actually paid for some of my more expensive hotel rooms! Choosing that brand of hotels also helped me feel safer and with most of their hotels it came with a list of activities, restaurants, shopping, etc...
3. Road Trip Theme - I toyed with the possibility of visiting all major theme and roller coaster parks, but I then decided that I wanted to see a lot more than just theme parks. My destinations were surrounded with what was offered in those cities and that helped me plan a route to take.
4. Packing Your Car - Living out of your car for 3 months can be tricky. Instead of having to worry about finding a store to restock my supplies, I bought almost everything in advanced. All of my clothes, shoes, toiletries, papers, etc... were placed in a specific spot in my car. I used a smaller suitcase to pack and unpack at each destination, I bought bigger bottles of the various products I needed but kept those in my car while filling smaller and less bulky bottles that I refilled as I went. I also reorganized my car a few times on my road trip, usually when I was at a person's house or at a more secure hotel. The more organized you are, the less of a hassle your trip will be!
5. Safety - I had my windows tinted on my car for more security and I also laid blankets over my clothes I had in my back seat. People won't steal what they don't know is there. Anything expensive or the extra cash I was carrying was locked in my trunk. I also carried 3 separate bottles of pepper spray (which actually ended up in a funny story I'll tell later) I was conscious of the other drivers on the road, I had my gps system and also paper copies of the routes I was taking, I never used rest stops, I had a portable doorstop alarm, I did almost all of my driving during the day, and I never ventured out on foot during the night. I also wore my keys around my neck and had the spare in one of the bags I kept with me in the hotel room, because I didn't want to run the risk of locking my keys in the car while repacking or unpacking things in my car.
6. Restaurants - Eating alone in a restaurant can be intimidating at first but it can also be an advantage since most restaurants have a bar where you don't have to wait to be seated and can still order off of the main menu. I wouldn't recommend drinking, if you drink, especially a woman dining and traveling alone, being aware of your surroundings and fighting off advances is key. Of course, just because you sit at the bar doesn't mean you have to drink :) You can flirt with the bartender, watch whatever sports are playing on the television and you won't feel so much like a dork when you're dining alone. If you want privacy and don't mind waiting for a table, I recommend bringing something to read with you or choosing that time to connect with your people through texting. Dining alone isn't so much taboo anymore and when you do get the occasional corny pick-up line like "whats a pretty lady like you dining alone for?" Telling them you're on a massive road trip explains it all and usually leads to some pretty interesting conversations.
7. People - Traveling through areas I've never been to before and worrying about what sort of characters I'd meet was something I was worried about at first. I went into that road trip thinking that I was going to have to stand guard 24/7 and zigzag around the icky people. I came out of that road trip with the converted knowledge that most people are genuinely good and have good intentions. Sure there are a few that would of tried to take advantage of me if I had let them, but there are certainly way more good people than bad. I had no problem meeting people and having interesting conversations with them. It was a great reassurance than good still out-weighs evil in this world! I never let my guard down but I also didn't let it rain on my parade and keep me from being out-going and welcoming to the locals and fellow travelers I met along the way!
