New to Design Work

Hi all! I have recently gotten into 3D design work. I am looking to take it up as a profession but need some help. I have a BS in Physics but not a lot of CAD experience. I have been using the FreeCAD 0.18 software to do my modeling and have built a few interesting things (simple hex bolts and lego bricks). I have a feeling I will either need to build up a portfolio of designs I have done or get some sort of certification to show I have some competency in this field of work. Does anyone have any suggestions or tips? Thanks!