First of all, there are 4 major carriers in the U.S. Cingular, Verizon, T-mobile and Sprint. Then there are some smaller carriers and some companies that resell time on the major carriers.
Determine where you are going to go and check the coverage maps. If you leave an area covered by your carrier you are roaming. Check to see what the carrier has to say about prepaid roaming. Some will not allow it, others may charge a premium.
And finally, consider how many minutes a month you are going to talk. If you you are going to talk quite a bit, or go outside of a carrier's coverage, you may want to consider a monthly plan. Cheaper and usually you can roam free of charge, or at least not as costly as the prepaid plans.
Finally, the phone. Get one that you are comfortable using, that you can understand how to use, and one that is easy for you to carry.

Im a 61 year old old fart,and doesnt understand this crap.Basicly Im going to be doing some traveling, and want to buy a prepaid cell phone.Can I buy a phone and pick up pre paid cell cards along my travels.From what I understand if I buy a T-Mobil Phone for example,and no matter where I end up I can go to a T-Mobile store front buy a card and activate it.I also heard about some hidden charges like roaming.How do they charge me or do they subtract minutes off my card to adjust for that charge.

ATTENTION SELLERS! I dont no if u can sell on this forum but if u can
Im an easy sell If I can get this to work. Thanks