said by bolt17cdn: You sound like a man that has many years experience in the industry.
Before moving into the role I have now, I spent a lot of time engaging small to medium sized businesses and their owners. I spent a good five years focusing on the best hardware, the best software, the best optimizations for that setup; the second decade was spent learning that I should have been focusing on the people using all that stuff.
If I was better with remembering quotes, I'd paste something about experiences and mistakes and how well you learn from recovering from them. While I've made enough of my own, the most educational mistakes I've encountered were the ones I inherited from other other service providers and administrators that were given the boot for making their epic mistakes.
The happiest people I've encountered are the ones that don't go over the sensible budgets they've made and things are running smoothly. They didn't spend a lot, their systems are running smoothly and they feel safe that their data is well protected. The customer experience should be your top priority in maintaining small business clients.
I think your number 1 priority should be considering how well you'll recover from a broken piece of equipment or data loss. Failed hard drive? You have a hot spare for your RAID5 array and you've entered appropriate email information in the controller software to contact you. Failed power supply? Well, you don't have a hot swap situation and the client can suffer a few hours of downtime while they wait for you, so you buy a spare power supply and leave it with the client. Deleted files? First order of business should be enabling volume shadow copies so you can quickly recover deleted files or mistakenly changed files. Then make sure you have a reliable backup method that you re-evaluate every once in a while - too many companies rely on a backup method that hasn't worked for ages since nobody checked it.
Preparedness ensures that you don't panic when something serious happens and displaying your preparedness to the client gives them that peace of mind.
Also, don't buy from a small time local company that hasn't been around a while. If you're going to be selling hardware, sign up with Synnex and become an Intel partner to sell their server solutions.
Feel free to PM me if you ever have any questions, I try to stay on top of technologies, new equipment, even new part numbers for equipment (one of my part time jobs involves me refreshing product line components for a company, knowing how they integrate).