get one's feet wet
Embark on a new venture, start into new territory. For example, I've only had a few cello lessons—I've barely gotten my feet wet. This expression alludes to the timid swimmer slowly getting into the water. [Late 1500s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.