When applauding, you need to clap your palms together firmly.
Tips
memory
Literally 'hand-palm': 手 (hand) + 掌 (palm). The character 掌 shows up wherever palms do real work — 鼓掌 (to applaud), 掌握 (to master, to grasp), 掌控 (to control), and the idiom 易如反掌 'as easy as flipping one's palm'.
usage
Both literal and figurative. 手掌 almost always refers to the anatomical palm; the figurative 'sphere of control' sense is usually expressed with 掌中 or 掌握 rather than 手掌 alone.