One current expression I hear when I visit the US, and sometimes read online, is this ain't my first rodeo. A rodeo is an event that has competitions in "cowboy" skills like bull riding. This ain't my first rodeo means that I have experience, that I've done this before. Here's an example:
Bob: Are you sure you're prepared for the presentation?
Kate: This ain't my first rodeo, Bob. Don't worry!