Generally, with a 640+ credit score and 5-7% down payment, you can secure a conventional home loan no problem

At the time, my credit was good but not great and that's what I was offered. 

Here are the Required LTV's:Primary Homes:-1-4 Units-620 FICO Minimum (660 High Balance)-95% LTV 1 Unit-85% LTV 2 Unit-75% LTV 3-4 Unit- Minimum 680 Credit scoreSecond Homes -1 Unit - 90% LTV -700 FICO Minimum Investment Properties:-1 Unit - 85% LTV Purchase Only (75% LTV Limited Cash Out)- 720 FICO Minimum

Spreadsheet template:TOP HALF OF PAGE:Addresses of comps - price - date - bed/bath - special feature(s) of house - conditionProperties listed here with dataMedian / Mean / Lowest / Highest chartCommentaryBOTTOM HALF OF PAGE:Left side, improvements since purchase bullet points.Right side, details about how/why you got the property for less than fair market value, again bullet points. 

Or do they have to do improvements?

In the alternative, you would want some kind of standby credit.

We do not yet have a credit card set up for those LLCs. 

These tenants usually have a decent credit score and care about keeping it that way.

I've established my line of credit, I already have an investing real estate agent in mind and I'm not afraid to personally do some of the work on these flips. 

Does his having lived there for a year and having paid his rent/ rent credits otherwise make him a more qualified borrower?