There's a few general things you might want to do before you try to "get connected":
Nationwide ISP - Get a nationwide internet service provider (ISP). I use EarthLink, but I suppose there are others equally as good. What you don't want is a small local ISP that will work fine as long as you're at "home", but has no local phone numbers outside the immediate area. You may save a little money, but they're of no value when you're traveling. If you need an "ISP Tutorial", click here.
Toll-free ISP - Get the ISP's toll-free (800 or whatever) number in case you get into an area where they don't have a number. With Mindspring, you'll find info on their website telling you how to get set up on their toll-free number. You have to tell them you want the access, then they'll email you back telling you the toll-free number and letting you know that your username is signed up for the service. They then charge you 10 cents (or so) per minute when you use the number.
Long Cords - Carry a long extension cord and phone cord with you in case you have to "stretch" to get to the connection. I've got several extension cords of various lengths, and phone cords 20', 50', and 100' long. I've used all of these on different occasions. Awhile back, I parked in a friend's yard for a week or so and used my 100' extension cord, 100' phone cord, and 100' TV cable line -- was completely set up with everything I needed to conveniently do my internet investing. By the way, a little-known fact about phones is that there's a little "interface box" outside that you can plug your cord into to "tap" into their phone line so you don't have to string your phone cord through their window and all around the inside of their house. It's of course up to you then to make sure you don't interfere with their use of the phone. I was able to get in all the time I needed when my host was asleep and when he went to work during the day. Finally, another little-known fact is that this interface box in rural locations is actually on a power pole out near the road. This makes it really easy to tap into any friend's phone, whether they're at home or not. And make sure it's a friend's house and that they're aware of your plan ... lol.
Splitter Plugs - Go to Walmart or Radio Shack and get yourself some of the "splitter" plugs. I'm not sure exactly what they're called, but they allow you to plug two male phone cords into one female connector. This allows you to link your phone line into a friend's setup, while still leaving their phone plugged in.
Cheap Phone - While writing about the splitter plug, I looked at mine here in the RV and was reminded of one more hint. I went to Walmart and picked up a phone for $7.95, then plugged both my laptop and phone into one of those splitter plugs. This gives me a phone to use now and then (on those rare occasions that I'm not on the laptop) but, more importantly, I use it to call into the local ISP number before trying it from the computer. I set this up after several occasions when I unsuccessfully tried to plug in and spent an inordinate amount of time trying to fix the computer's internet setup, only to finally find out there was either a problem with the phone line or with the phone number. Checking it out first with the phone has since saved me much time and frustration.
Free Internet - Sign up with one or more of the "free internet" ISPs. Click here for a list of free ISPs and my evaluation of them. Having an alternate to your primary ISP will give you a backup if either your ISP doesn't have a local phone number at your current location or if the number is busy or otherwise unacceptable. After using them for awhile, I'd recommend actually using the free ISPs as your primary access mode if you want to save some money. Some of the free ISPs do is put a small advertisement on your screen in return for the free access, but the evalution linked to above also tells you about some of the newer ones that are completely ad-free.
Nothing in this site is copyrighted -- I'd be honored if you'd reuse anything you find here for your website
2007 UPDATE: Since the advent of WiFi, the information below relating to dialup service is virtually obsolete. It's been left here for those few that still have dialup. For information on WiFi and other high-speed internet access options, visit my InternetOnTheRoad.com website.