Books are important to maintain because it keeps track of the performance of the partnership not only for one year but over several years.Partners normally have the right to inspect the books.Will the accountant you work with either maintain the books for you or help you make sure its done correctly?

I agree with @Chris Seveney that a performing note would be a very good starting point.

If you are buying a BRRRR then make sure your rehab budget and ARV make sense and is accurate. 

Small multifamily, up to 4 units (at least to start), then graduate into larger investments as your portfolio performs positively. 

I can assure you, your business will perform far better as well.  

Quote from @Jonathan Greene: Never sell a high-performing property with no cap ex and low maintenance to buy another rental.

Make sure you don't chase deals where you can't perform.

They don't guarantee their performance and your money is lost if they flee with it. 4.

I definitely recommend that you seek out a Certified Cost Segregation Professional so that you are confident in the quality of the work performed and the deliverables produced.

I may also charge if one of our people can't perform scheduled maintenance because the tenant has not crated an aggressive dog.