Need help in buying other rentals

[Lea Morgan]

Hello to Everyone, I am a single female mother looking to retire in the next few years from my rental income. I currently own two single family homes free and clear and collect $1,300 monthly from the two. I have just recently Incorporated my rentals into a LLC and have one business credit card with capital one with a credit line of $2,000. I am looking for information on how to establish a high line of Business Credit as well as a how to go about getting a loan to purchase other properties. My goal for 2015 is to purchase three more properties. I live in a area where I could buy a rental single family house for around $25-35 thousand and collect roughly $650 for 2bed and $700 for 3bed. My state is Iowa. Thanks in advance