Montuno is the name given to the melodic rhythm articulated by the piano and it takes the form of a two to four chord repeated pattern (also called a vamp), although it can be longer. The basic montuno structure is simple to learn, although its syncopated nature and the essential phrasing to clave provide unique and rewarding challenges for the pianist.
Montunos are, to the newly initiated, fairly restrictive in nature as they comprise a small number of chords. True montuno mastery involves continually engaging the listener's interest in the face of this limitation through changes in chord voicings, timings and tasteful use of adornments like passing notes, all the while maintaining the flow as a backdrop for the instrument melodies.
Of foremost consideration to the musician is portability. If you're lucky enough to have a venue where a full acoustic piano is available, I envy you. If you intend on gigging, then electric pianos or synthesizers/keyboards are probably most practical.
Electric pianos feature a similar key action to acoustic pianos, which I consider essential to developing a pianist's touch and phrasing. I also prefer the flexibility of the full 88 keys where available. This does lead to a somewhat heavier and more bulky unit.
Synths or keyboards can be much lighter and there are many instances where two of them are used in place of one full electric piano. There is generally more flexibility in how they can be configured. Synths are commonly found in many timba bands, although usually in tandem with an electric piano as well.
Alternatively you can have a combination of both.
If your group does not have a bassist, the pianist can and does assume the bassist's role; playing the bass tumbao with the left hand. Some electric pianos can be configured to simulate bass sounds on the lower half of the keyboard; otherwise a synth can be used instead.
Some brands worth investigating are Korg, Roland, and Yamaha.
What to play
The best place to start is with the I-IV-V-IV progression. A number of salsa standards are based on this progression, and once you're familiar with it, it's very simple to identify.
Keys to start off with are C major then A minor. Remember that brass and woodwind transposing instruments are common in the salsa line-up, hence many songs are written in keys that are friendly to them such as F major, D minor, and G minor.
Two other common progressions are the I-V-V-I and the II-V-I-I, and you should try them in the above keys as well.
Pianists are extremely fortunate to have a fine piece of instructional material available to them called "101 Montunos" which details the playing of the above. I strongly recommend that you purchase it if you are at all keen to play Afro-Cuban piano.
Salsa Guidebook For Piano & Ensemble by Rebeca Mauleón. (External link)
101 Montunos by Rebeca Mauleón. Contrary to the title, there aren't 101 montunos listed in order. Instead the approach is skills-based; teaching you how montunos work, how to play them, and providing plenty of case studies. A truly exceptional piece of instructional material. (External link)
Other references can be found under the Instructional > Piano/Keyboards category of Descarga.com. (External link)
& Merengue Society