The trick is to try to separate your emotions from the decision. 

We’d all be naïve to think the gravy train will last forever, so it’s important to think ahead strategically.This is a great point...We were a one-trick pony (REOs that needed $20-30K in rehab) for the first several years in this business.

I'm surprised @Brian Gibbons as he has not mentioned being a transaction engineer yet or stuck as a one trick pony. :)

The trick is knowing exactly what these bureaucrats are thinking and how to prove them wrong.

The trick to hard money is to make sure you are only using it for a very short amount of time, and have multiple options to get out from under the hard money loan.   

The trick has been finding a bank that understands this.

But getting in for the $ wanted, that's going to be the trick.

@Andrew Lee Check out the  Bigger Pockets Rental Property Calculator which can help you with your analysis and has tips and tricks on how to fill in some of the numbers.

Doing the calculations if you live in an area with tiered electrical charges is the hardest part but you should be able to come up with a spreadsheet to do the trick.

The biggest "secret and strategy" that I ever learned was this:If I wanted to be successful in this business, I had to be able and willing to do things that others either would not or could not do.Since then, I have also learned a few tricks and strategies that I do keep secret to myself, because they give me a competitive advantage.