Tuning once a year is recommended for the majority of pianos. When used more intensely or for performance then tuning more often is recommended.
Voicing of the hammers is tone regulation of the sound strings produce when struck. Making the hammers harder or softer is one of many approaches to improve the voice.
Regulation of the keyboard and action will bring balance and improve the touch when performing. Sticky keys, lazy hammers old dampers can also be part performance issues.