New here and new to REI

My name is James and I live in the Augusta GA area. I have purchased a couple distressed homes during the bust and did ok with rehabbing, living in them for a few years, and then selling for a profit. I purchased my first rental a year ago and am now up to 4 rental properties. My problem now seems to be credit/debt ratios because I used conventional 20% down mortgages on the 4 rentals plus my primary but want to continue to acquire properties. I am looking forward to learning all I can here and hopefully help some others.