An electric or digital piano is a good choice. Here are some key points you need to know:
- Go for the largest number of keys (88 keys is the standard).
- A hammer-action/weighted feature is very important since most training, such as the Hannon exercises, are traditional and include proper hand gestures, positions, etc. Here for more info.
- A built-in metronome is also very important. But no worries, almost all e-pianos today have metronome installed on it.
- Velocity sensitivity - the harder you press, the louder it sounds.
NOTE: BEWARE OF CONTROLLER KEYBOARDS Unless you are familiar with them and know how to use them, then avoid controller keyboards. But learning how to use them has a lot of technicalities that you should know --they are not your typical "Plug-and-Play" keyboards.
http://madsenstudios.com/info/a-guide-to-buying-an-digital-piano/
