Your Better Business Bureau has some tips to help you make an informed decision. If the ISP gives you a long distance access number, you may end up paying more in long distance charges than you do for the service. If you live in a large or medium sized city, you shouldn't have any problem finding an ISP with a local access number. If you live in a rural area, you may have to use a long distance access number. In this case you should be sure you have the best long distance rates you can find.
Most providers offer a monthly fixed, flat rate with unlimited online time.
If you're only interested in surfing for brief amounts of time or if you only need email access, look for pricing that reflects actual time spent online. You might be able to obtain discounts for paying with a credit card or for paying for three or more months at a time. Keep in mind that the lowest price may not always be the best deal. Especially if you are new to the Internet, you should look for an ISP that will help you get up and running. It's a good idea to try the number out before you sign up to see how often you get a busy signal or how long you have to hold.