Creating curves with the pen tool in Adobe Illustrator is a good challenge. Check out this video on both drawing and editing with the pen tool. Click once in a place and then drag. This pulls out the direction handles.
Check out this tutorial video from Sessions Online Schools of Art & Design's "Illustrator Basics" course. Part of Sessions' Graphic and Marketing Design certificate programs.
Have an iPhone? Check out all 200+ new features coming in iOS 13.