I don't feel it's possible to work out every last detail and know what the future holds, but you should have a firm grip on the basic math before you jump into investing.The real bottom line for me when I started was positive cashflow (although I couldn't articulate it then).  

As Doug alluded above, you need to sit down and do the math to see if the reduce interest cost of your new mortgage would offset the early pre-payment penalty on your current mortgage.  

If a newbie does their research and homework before investing I see no reason why they shouldn't use private money. 

I always look at the math before I invest in a property and like to share with others to see if anyone else has something to add.Here is  sample of my latest deal - I use Google Sheets to store all my documents so I can review and update it anywhere:

Pretty good biz before the crash.Kinda got to do the math on the 1031.

It's not absolute, it's a math question. 

When you say cash-on-cash returns, are you simply doing the math to determine how long it will take for you to make your initial investment amount back? 

You'll never be sorry that you did.Now there are pitfalls to be avoided--do your homework!

You'll be able to put as small as 3% down (verify that, I'm not 100% sure-but I know it's a low %).You have to do the math to know if you've got a good deal.  

Using a little basic math and intuition, I know that after this deal I'll be stuck on the side lines for a while until my RE and personal income can refill the capital coffers for the next acquisition....unless.......unless there was another way!