What to do with money while saving for a downpayment?

[Mike Koscielak]

I'm brand new to this forum and I'm amazed at how supportive this community is of one another. I'm about 100 podcasts in on both Bigger Pockets podcasts and the How to Money podcast combined, plowed my way through the Rich Dad Poor Dad and Set for Life books, but I haven't come across the information of what to do with money when saving up for a down payment on a rental property in the Milwaukee area. I have about $15k sitting idle in a savings account, which I've learned is not using it effectively. I need the money to stay liquid for when I reach that point of knowing how to spot a deal. Any suggestions are appreciated!