Work your way from top to bottom first with your plan, start backwards, think of your goals and how to get there, look at specific strategy vehicles to get you there, learn them, and find ways to start applying them in real life.

Also, some vehicle expenses.What about computers, printers, etc?

Thoughts on the best vehicles to pull equity out while keeping the owned properties in a good cash flow position.

In the upper left under vehicle storage, select either Boat or RV storage, doesn't matter.

Houston is home to more than 20 Fortune 500 company headquarters and has the third largest number of Fortune 1000 companies in the world, such as Sysco, Walmart, Waste Management, Memorial Hermann Health System, Kinder Morgan, AT&T, ConocoPhillips, United Airlines.Houston ranks No. 2 in manufacturing GDP in the U.S. with a skilled workforce of more than 230,000 industrial workers in specialties such as fabricated metal, machinery and chemical manufacturing.

Thousands of homes in TX, LA, & FL are dealing with flood damage right now that are not in flood zones.Workers Compensation coverage if you have anyone on payroll, any subcontractors that do not have their own coverage, or if you have any Statutory employees (most common would be realtors).Business Auto may be needed depending on the ownership, size, type, and use of the vehicles used to service the properties.Equipment coverage may be needed if you have Tools and Equipment you use to maintain the property such as Tractors, Bobcats, power washers, generators, etc.Builders Risk policy could be needed if you are renovating a property before renting it out.Hope this helps with some possible policies you may need.  

And no one will have any idea who's trash or unlicensed and broken down vehicle is in the garage.A better plan is (depending on your market) try to locate professionals, or grad students that are looking to share a large rental with nice finishes and amenities.

Why not use a HELOC when the time comes as the vehicle to pull out additional cash for the down payment on the next property? 

Majority of people use it as an investment vehicle, OP.

Tenant responsibilities, payment due dates and allowable methods, late charges, the "joint and several" clause, adding/removing someone from the Agreement, yard maintenance expectations (which are also spelled out in the Agreement), vehicle requirements, etc. etc.