[Konan's able to provide a reasonably academic explanation.]

Everyone who can use chakra is born with an elemental affinity - one element that they will be more naturally able to work with than others. Then the rest comes down to individual training.

There are handseals that help to mold chakra in various ways, and combinations of the handseals used in rapid succession will create specific results. Then there's the issue of chakra control. Healing someone with chakra requires more refined control than any other type of technique.