set (one's) hand to

1. To sign something, such as a document. As soon as you set your hand to these papers, you'll be the proud owner of a brand new car! I would never set my hand to such an unfavorable contract—I think my signature was forged.

2. To do or attempt (something). I'm pretty good at any sport I set my hand to, except golf—my swing is still terrible despite lots of practice.