Another useful skill is hearing and playing the "tumbao" on the congas, especially for On2 dancers. After you hear this rhythmic pattern, you will see why it is called the tumbao. Actually, it should be called the "tumtumbao".
Nate Torres, a young musician from Bronx, NY, filmed a 7-part series of instructional videos that teaches basic conga techniques. Notice his New York accent.
Video 4 explains how to play the basic tumbao rhythm.
If you have taken taking Eddie Torres' class, he sometimes quotes Tito Puente saying that the On2 Salsa step is very natural because it compliments the tumbao slap on the 2nd and 6th beats.
Videos 1-3 explain how to play basic sounds on the congas. Videos 5-7 explains more intricate percussion patterns.