set your hand to

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.
See also: hand, set

set (or put) your hand to

start work on.
A fuller version of this phrase is set your hand to the plough , which alludes to Luke 9:62: ‘No man, having put his hand to the plough, and looking back, is fit for the kingdom of God’.
See also: hand, set