For clients you bill regularly, you can schedule invoices to send automatically, so you don’t have to do it manually every time.

Things change regularly and I would truly be interested in hearing from investors "everywhere". 

If after adding the additional monthly recurring costs (electricity, gas, water, internet, insurance, lawn care, snow plowing, etc.) to the standard long-term costs (Mortgage, taxes, regular insurance, etc.) the property won't net at least $100 if I can get the average rent I see on FF for that area, then the property isn't worth more investigation.

Instead, just make it a habit to show up regularly and deliver amazing content.

We’ve had great success with our listings, regularly achieving 5x the market average ADR on Airbnb and receiving frequent offers from local realtors to purchase.We’re now considering scaling up with a new project and have been approached by a friend who’s interested in partnering with us, providing financing for renovations.

If you have been using expensive vendors, consider switching to more affordable service providers or negotiating bulk discounts for regular services like landscaping or repairs.

You could not pay me to use the service and BP should not promote them.

If 80% of $4,200 ended up on the depreciation line (in addition to the regular depreciation of the building) - you are fine. 

So for example, if you know your goal is to move away from NYC/LI possibly because of a potential future promotion in 5 years and you also want a lot of cashflow/appreciation before you move... then it may not work for you. 

You do not state what is actually "breaking" with your systems, but AC's generally last longer than many other appliances when they are properly and regularly serviced.