record keeping for small rental portfolio

[Jane A.]

Once a year during tax season the question of a better record keeping hits me :)  We manage about 20 rental units and once a year I need to go through all our business accounts statements and credit cards to sort through records for the whole year.  At the same time, I try to keep all receipts for every unit in a separate folder.  I tried to keep all current records in the online excel sheet, so it will be easier to track all expenses, but I need some discipline to go there every time.  I am about to get a real notebook to keep records of expenses which were paid cash with real signatures of contractors.  Did somebody find a better way for record keeping?  It is my side business, I want to keep things as simple as possible.