for invoicing and keeping up with accounts receivable, we started with quickbooks simple start and then upgraded to quickbooks pro. for cash flow and keeping up with expense items in check book form my book keeper uses quicken. That creates nice looking income statements and statement of cash flows that Bankers like for loans. for routing regular bulb service there are several calendar programs available for free on the internet we have used. They all take time to input info, but work.
I have used Peachtree accounting, Lawn Monkey, Clip, and lawn pro, and the above is the easiest and least expensive way to do it for me.