In “classical” and related kinds of music, we are often asked to make our instrumental music sing or dance. In fact, most music of this type should do one or the other.
Singing-type music may be labeled as such with markings like cantabile or vocal-ish titles like “Aria” or “Chanson.” Or it may be characterized by notational features like long, slurred lines. In any case, playing through the melody, you can probably intuit whether it is song-like (or dance-like).
To give your musical line a singing quality, focus on making long, smooth, elegantly-shaped phrases. They should sync with the underlying pulse without drawing attention to it.
To make your lines dance, bring out the meter, by creating a sense that the beats are not all equal. This might be indicated in the notation with accents (dynamic, agogic, tonic, etc.). Or it might require some brief research into the kind of dance: for example, a quick search will show you that a Sarabande is generally in a slow three, with stress on beat 2. Some dances have rhythmic characteristics like clave that puts stress on certain subdivisions of beats.
If your music seems to have an unspecified dance-like quality, start by bringing out the typical hierarchy of beats: in 4/4, for example, beat 1 is the strongest, beat 3 the next-strongest, beats 2 and 4 less strong, and the “ands” weaker still.
It’s common for a multi-movement piece to have both song-like and dance-like movements, and even for both approaches to appear within a single movement or short piece.
Here’s just one excellent example of singing vs. dancing in instrumental music. Listen to ToniMarie Marchioni and Jacob Campbell play the beginning of the first movement (“Aria”) of the Dutilleux oboe sonata, and notice the smooth, shaped, singing oboe lines that overlay the pulse without emphasizing it:
Now skip ahead to the beginning of the second movement (“Scherzo: Vif”) and notice how the oboe line is accented, bringing the pulse to the forefront in a dance-like way:
The next time you pick up your instrument, ask yourself whether the music should sing or dance, and what you can do to make that happen.