Running Number? Two Part Question

[Adam Read]

When you are running your numbers do you use the Calculators here on the BP; if so do you run additional numbers along side it? 

If not how do you run your numbers?

I'm referring towards buy and hold, rentals.  

I'm new to real estate investing and still very much in the learning stage. Any additional information would be very helpful. I'm on the MLS listings practicing analyzing deals weekly to get a good feel for how the process works. I just want to make sure since I'm so new that I'm not over looking anything.

Thanks BP