These are real costs that hit your bottom line whether you like it or not.The biggest mistake I see from new investors is taking the revenue and minusing the mortgage payment and calling that cash flow.

The only exception is when we have "Santa Ana" winds from the East in the fall, which are absolutely glorious days on the coast, but summer tends to be one of the worst weather seasons.

You can hear real-world examples of how others have built their investment portfolio and (hopefully) learn to avoid their mistakes.4.

I just want to be prepared for the worst and act immediately if anything happens. 

Don't make the same mistake I did.2.) 

A genius learns from others' mistakes. 

@Daniel BaradRecommend exploring as many sources as possible to get referrals AND cross-reference them to get as much accurate information as possible.Check out NARPM.com, BP’s Property Manager Finder (BiggerPockets: The Real Estate Investing Social Network), etc.Also, encourage you to learn from the mistakes of others - by reading posts here on BiggerPockets about owners not having their expectations met by their current Property Management Company.

Don’t want to emulate that mistake in real estate by allowing myself to become too influenced by companies that are simply good marketing their own services but not great market prognosticators.

Sometimes people want to learn and go through the process of self-managing and making mistakes, other times people realize that that thought may not be wise and choose to hand it to someone they trust. 

The one I used was the worst workmanship I've encountered and didn't complete the job either.