Choose a service first, then choose a phone. Reviewers say that network functionality and customer service are more important than the specific phone. Most national carriers and many regional carriers offer similar selections of phones in all categories, although specific models can vary.
Estimate the amount of data you need. While charges can quickly mount if you exceed your plan's data allowance, consider starting with a lower data amount but keep a careful watch on your usage. With careful management -- using Wi-Fi at home, in the office or in available hotspots, for example -- data consumption can be lower than you might expect. On the other hand, if you like to stream movies and even music while on the go, you will burn through tons of data. If that's you, consider an unlimited plan from T-Mobile or Sprint, the only national carriers to offer them.
Check data overage charges. Read the fine print about how you're charged if you go over your monthly data allotment. Some plans will charge you extra per GB while others will just drop you down to a slower data transfer speed. Keep in mind that even with unlimited plans, you are only unlimited while on your carrier's network and data usage; roaming is still subject to a cap.
Check the coverage area. Carriers have coverage maps on their websites. Most have good coverage in cities where they offer service, but things can be markedly different in suburban or rural areas. Check voice as well as data coverage. For data, check if a proposed carrier offers LTE or a lower-speed service. In addition to checking coverage near your home, check coverage at your job or school, as well as in areas where you frequently travel.
Consider a prepaid cell phone plan. With some carriers like T-Mobile, for example, you don't have to be locked into a contract to have a postpaid plan. However, if you don't want to go through a credit check, a prepaid cell phone could a good option. See our report on prepaid cell phone plans for more information.
Ask friends and neighbors. Cell phone service performance can vary greatly. Do your own informal poll of people in your area. Those who live or work in your neighborhood can tell you how frequently they experience outages, busy networks or dropped calls.