Price- The $19.95 unlimited access rate is fairly commonplace. If anyone is asking more they better have a good reason for it, otherwise don't bother. It's better to stay away from hourly rates (better to spend the time getting the information you need rather than watching the clock).
Staying Power - In the current Internet market place, businesses come and go with the drop of a hat. An ISP that's been around for a few years will have proven itself and gotten enough experience to provide quality support. As a rule, stay away from brand new ISPs.
Access and Connection Speeds - Your modem will only connect at its top speed if the modem it's connecting to has the same speed capacity. 33.6 kilobytes per second is pretty standard. However if you have a 56k modem, check the manual to see if it's x2, Kflex or V. 90, then check to see if the ISP supports it. Also remember, your computer is making a phone call to connect, so make sure the ISP's dial-up number is a local call.
Users to Modem Ratio - Busy signals are sometimes a problem in the ISP business. How many connections an ISP can provide depends on the number of modems it has. If an ISP only has 50 modems, then they can only handle 50 calls at a single time. Be sure to ask a prospective ISP what their user-to-modem ratio is. Lower is better, if the customer-to-modem ratio is greater than 10 to 1 (that is 10 customers for every modem), you'll probably hear busy signals.
Technical Support - Despite the ease of use that everyone is talking about in regard to the Internet, you're still using some pretty sophisticated pieces of equipment. An ISP's ability to give good support services can mean the difference between the ability to connect or not. Try to judge an ISP's ability to provide technical information in a language that you can understand.
Personal Web Pages - Many ISP's are offering space for people to create their own web pages. You may be able to receive free space on their web "host" computers. Often these "hosts" are slower than the commercial ones but they're a great way for your organization to establish a presence.
Regional vs. National ISP's - This dilemma can be a little like going to the little local bookstore or going to the big national chain. If you go with a local provider, your $19.95 a month is helping to fuel the local economy. However, there are a few things to consider before signing up with the local guy. Are you going to be doing a lot of travelling out of your region? If so, it may be better to go with the national company that can provide you with local dial-up numbers no matter where you go. It's important to note that there are a few national ISPs, like Internet Global Communications (contact (415) 561-6100, www.igc.org, or igc-info@igc.apc.org).