We found that for commercial accounts, it's essential to know who their customers are and what they expect. For instance, a resort hotel or HOA's customers pay to use the pool, which could be why they chose that place. If the pool is gross or closed due to equipment issues, customers will get mad at the front desk, management company, or the lifeguard. Check if your county health department puts their pool inspection reports online; it's great to know about any past problems, especially if they led to a closure. Also, look at reports for similar properties to understand what else the inspectors are looking for. We use this knowledge to better prepare ourselves during the walk-thru and pitch to the property manager. Also, if you can talk to the staff, see if they have any info that can also help. 

You can also just call the inspection office and ask questions; in our area, we often talk to them about recently introduced guidelines or clarifications of existing rules. The inspectors are responsible for enforcing the rules, and the ones I’ve interacted with don’t like being the bad guys. Still, they have a job to do and only shut things down when there is a true water quality or safety issue. They can be a valuable ally to have. 

We branched into commercial (or small commercial - HMAC) pools, and are currently getting our complete staff CPO certified.  What we have found is:

Over insure - every property has different ways, or third party vendors, to check your insurance.  you will have to have plenty

Price High - not many companies will jump through the hoops (or not many smaller ones) that are there for commercial properties and that takes time on your part, which equals money

Relationships - Inspectors are people, they want to see that what they recommend is being put into place, and they want to see constant improvement.  The inspector interprets the rules, and each inspector (like it or not) will interpret the rule differently

Exclusivity - once you command that space, even in a small town, you will command a lot of respect for your knowledge.  Treat that like the responsibility that it is, and learn, learn, learn

There’s a lot more, but for now focus on that and you will be having fun.