I use some ancient software, circa 1987. MS Dos program called Telemagic. It is fantastic.
It keeps notes on every transaction, phone call, address. It will schedule all my work, and print reports on anything due or scheduled. It keeps inventory of all my tools, trucks, etc, including serial numbers, parts ordered, whatever I choose to put in it. Unfortunately, there are no upgrades to anything modern, and keeping that dinosaur running is starting to get tricky. One valuable consideration: unlike most modern software, it isn't a "subscription" service, and costs me nothing to continue to use.
I track all my trucks on OneStepGPS. Less than $15/month/vehicle. Live reporting, I know where everything is at all times, and can also generate DOT annual mileage reports per state, or anything else I want to calculate. Their customer service is beyond good! They always answer the phone (California business hours), and they will even write your reports for you, if you cannot figure out how to do it yourself. No devices to purchase for installation, either. All covered by the monthly fee.
Accounting by Sage Software, formerly Peachtree accounting. Too damned expensive, and difficult to use. I don't recommend, but I'm stuck with it right now.