Money for growing real estate portfolio

Hello Bigger Pockets, 

Some background, I am 25 and bought a rental property about 4 months ago. I was able to get it rented and am making great cash flow looking to do it again. I was wondering about tips for upscaling/ how to go about getting money for the next property. I went through the bank to get the loan on my first property, I am roughly 20k saved up but would like to keep that in my pocket if I can. 

Just looking for some advice about private money lending, buying houses for sale by owner or other ways to get money instead of going through a bank. 

Thank you,

Keyton