How to be a musical dancer

A lot of dance learners can count for their dances, but they only count their counts regardless how the music goes. For example, they may count a '2, 3, 41' for a rumba, but counting the '2' at the beat one. Another example is that they tend to count faster and faster as their mood get higher, and could not hear the beat in the music. For many dance learners, the reason for these is that they do not know when the music starts.

The Beat
Normal people focus their attention on the melody or lyrics, or even particular instruments,, musicians also mind the tempo, and various accents in the music. These are all good for choreography, since choreographer usually wants to fit steps and actions into a song of their choice, in order to create special impact. From a dancer's viewpoint, the beat is the most reliable cue because it has a high probablity of recurring in a predictable manner. To the trained ears like the competition dancers', recognizing the tempo and the first beat once the music starts is like an instinct. To the social dancers, missing the first few bars could not be a problem as the beat is very predictable, let the bodies sway for a few more bars and finally they can get the beat after a couple of attempts.
To the beginners, the first challenge is to separate the rhythm in the music (melody) from the beat (the underlying beat). Once you've identified the beat, you'll know the tempo, or how much time elaapses between the beats. Once a tempo is established, it is highly likely for popular dance songs to repeat at that same speed throughout a particular musical selection, except a retard or a fade out in the end. For men, it is a must to get the beat in order to lead; for ladies, it is also essential to understand the music as it helps when to anticipate a move.

Time Signature
Social dance music is structured based on the smallest unit of time, the beat. Social dance music can be roughly categorized into three basic time signature, 2/4, 3/4, 4/4. A two-beat song is likely that either polka or merengue music is being played. However, due to the fast tempos for both of these dances, it is easier to usse the option of counting in multiples of four to make it equivalent to 4/4 time. It also takes two bars or four beats before your standing foot is free again in the polka. A three-beat slmost signify waltz. If a four-beat is played, it coule be appropriate for any one of a variety of other social dance styles as most social dance music is 4/4. So in short, if you can count to four, it's easy to start your dancing at the right timing.
For the mathematical you, you know music has an order and consistency but never random. You need only be able to recognize and identify which cues in the music provide order and consistency and thus provide dancers with the most reliable information. The answer is the underlying beat, which is most often referred to as the beat.

Locate the Beat
To locate this underlying beat, you can listen for the heavier sounds in the music, such as the bass player's or the drummer's sounds, rather than the lighter sounds (melody). Because the duration of the notes within the melody may vary, it becomes an unreliable cue for dancers. Typically, the bass drum keeps all the musicians together at a certain consistent tempo, and this bass drum usually gives us the dancers the beats.
A dancer should identify the first beat in the bar (downbeat) so that footwork can be coordinated to the start of the music. Untrained ears would like to wait until after the introduction of a song is over and be ready to move on the first beat heard. However, it's hard to tell when the introduction ends for a newly heard song, although in general introduction lasts four to eight bars. Beginners might fit counting of three or four to see which best fits.
My practice is to count as soon as the music starts, and I'll know whether it's a three beats or four beats once I heard the next downbeat. I have about 1.5 bars' time to decide which style best fit, since the second half of the the second bar would be a count in advance, i.e. I count it 4&1 if I recognize it a Cha Cha Cha, or 41 if I recognize it a rumba.

Phrases
We have beat as the smallest unit, two / three / four beats group together to form a measure which we called bar, however, in setting routines, we usually group multiple measures, e.g. a 4 / 4 timing can be 1234, 2234, 3234, 4234, 5234, 6234, 7234, 8234 or 12345678, 22345678, 32345678, 42345678 while a 3 / 4 timing can be 123, 223, 323, 423, 523, 623, 723, 823 or 123456, 223456, 323456, 423456.

Tempo
As mentioned above, once you locate the beat, you know how much time you have between beats, then you have an idea about how many beats in a minute (beat per minute) or how many bars in a minute (bar per minute). This in turn, gives you an idea of how fast you should move. Professional dancers are able to count as bar per minute and beat per minute, as well as state the tempo of a particular dance style as bar per minute and beat per minute. However, social dance music uses only three different speeds (tempo): slow, moderate and fast and mostly identify the tempo as beat per minute. Tempo varies between songs, but it is very likely to be consistent within a particular song. We have also developed typical tempos for the most popular rhythm dancing and smooth dancing.
Social Dance
Tempo (beat per minute, bpm)
Waltz
90-105
Foxtrot
120
Swing
120-170
Polka
96-130
Cha Cha Cha
120
Merengue
125-140
Rumba
120
Tango
130
Salsa
150

Accent
Particular styling cues that are characteristic of certain types of music are introduced through the melody and its overlying rhythms. For example, a Latin flavor may be added with certain instruments, such as maracas or bongos, which often subdivide selected beats within a song that are characteristic of cha-cha, rumba, merengue, salsa, mambo.
An accent occurs whenever a particular beat within a measure is made stronger, louder, or heavier or otherwise stands out differently from the underlying beats. Dancers may choose to accent their movements on selected beats, which can be subjective and reflective of personal styling and thus not reliable music cues. Accents are superimposed on the underlying beats whether by a dancer's styling or characteristics of selected genres of music. Thus accents are more subjectivee and may be altered by different musicians' interpretations of a particular song, making this information less reliable for dancers.
However, certain accents that are consistently used within a measure can alert you to what type of dance music is being played. e.g. Waltz music's count 1 is slightly different, in both swing and foxtrot music, both counts 2 and 4 are stronger because the upbeats are accented in each measure.

It is advantageous to know the music structure if you want to be a good dancer. It takes time to practice to get the first beat. And it takes time to match the rhythm of your feet to the rhythm of the song. Keen dancers usually have experienced ears, if not musically trained, it is not because keen dancers are talented, it only means that they love dancing and want to improve and they really do their homework on musicality. I know a number of 'dancers' who do not care about the quality of dance as long as they are having fun, however, it is up to you to decide to be the one who think yourself can dance, or to be the one whom every one thinks you can dance.