Inherited rental properties - Where do I start?

[Dan Creed]

First timer here. My dad passed away recently and left 3 properties to my siblings and I in a trust. 2 of the properties are multi-family rental units. All units are rented and are cashflowing. The third property is a vacant single family home (60s era) that my dad and I planned on gutting and turning into a 2 unit rental but thats another topic. Properties are all paid off. He was old school, very organized, maintained all of the properties on his own and did all of his "books" on paper in ledger notebooks. 

I am sole trustee and will continue to manage and maintain the properties on my own for the foreseeable future. Big shoes to fill but I am looking to find an efficient way to track the income/expenses and other financials. I think quickbooks might be too powerful of a program. Any suggestions for analyzing the financials for the current 7 units? apps? spreadsheet templates?