How to finance 2nd investment?

Hi , I recently purchased a duplex and live in one and rent another one . Got it for 2.7% on a fha loan . I’m currently trying to prepare on how to finance my 2nd investment in the coming years . Any advice on what you guys did right after you bought your first investment and how you guys finance the 2nd investment . I currently got 20k saved up and will try to save up even more in the next couple years.