Just like with any other model craft, there are hundreds of RC jet designs to choose from. Before purchasing, look around at several shops and websites so you can see all the options available before making your choice. There are so many styles so don't settle for something that doesn't suit you. Aside from the exterior look, there are also internal components that will decide the performance of your plane.
There are two main model jet engine types: gas powered engines and ducted electric engines. Both of these choices will provide your aircraft with good performance, but they have significant differences. Ducted engines are slower, but they are also cheaper and easy to maintain. Gas engines are much faster, but they are messy, difficult to fly, and expensive to purchase and maintain. However, experienced fliers should pick a gas engine because they provide the most authentic experience.
Turbine engines have recently been introduced to the RC jet market and they are redefining the way these planes fly. They are extremely expensive though, which is a prohibiting factor for many casual hobbyists. Some can fly as fast as 200mph, making them quite dangerous if flown improperly. As a general rule, these planes should only be flown by experience hobbyists who know how to properly control them.
Decide how many controls you want. The more maneuverable your aircraft is, the more enjoyable it will be flying it. But complex maneuvers require skill to perform, and can only be done with practice. Extremely maneuverable aircraft are also more difficult to control, even when they are flying straight. Beginners may want to settle for a less capable aircraft and then upgrade as they become more experienced.
RC jet aircrafts travel at extremely high speeds which generates a huge amount of noise. For this reason, these aircrafts have been banned in some areas. Certain planes fly at such high speeds that they require a license in order to fly them. Before ordering a jet online, make sure to check your area's standards regarding noise and speed control for flying a model jet or any other aircraft.