I was thinking that for nicer, more desirable neighborhoods, it might make sense to use 5% for vacancy and 5% for credit losses (10% total loss for vacancy and credit losses) and for tougher neighborhoods, to use 8% for each (15-16% total loss for vacancy and credit losses). 

Water is tougher as there's usually a lawn or shared area so you'd need 5 meters for a 4 unit property.

. -- that's a bit tougher.

Also, the properties that are 250k and under are being bought so quickly with Cash offers, so for our clients that are going through loans, its tougher. 

Your vacancy rate will be a little tougher to predict until you have a couple seasons/years under your belt.Generally, people determine a nightly rate for their property, then commonly offer a discounted weekly rate, and sometimes a further discounted monthly rate.

Hard Money is easy to find, private lenders are a bit tougher. 

Some states, counties and municipalities are tougher to evict in than others.

This is certainly a little tougher to do, but it is a more lucrative strategy.And never pay tax on capital gains!

On the buying side the market is definitely tougher than it has ever been. 

Over the years I’ve realized that the planning it requires to build to what I call “financial escape velocity,” is a lot tougher than it looks.I can only name a handful of folks I’ve seen over the last 12 years in lending that have “escaped,” so to speak and can share the strategies, tactics, and philosophies of what it takes.