Be sure that this form of exercising meets your needs and gives you pleasure. A good machine has handles with adjustable resistance levels. The seat should be comfortable. Straps on the rotating footrests hold your feet firmly in position. Some machines have an ergometer that shows your speed, distance traveled, and calories burned.
Lightweight machines fold up and store in a closet.
When shopping for a rowing machine, ask lots of questions. Be sure the machine sits solidly on the floor. Whether it has a single bar or two pull handles, the movement of the oars and seat should be smooth. Test the rowing machine long enough to see if it will be comfortable and user friendly. If you are a beginner, work out with a certified exercise leader.