Must know RE investment formulas?

[Andrew Rodriguez]

As a young future investor I have been trying to do some practice runs on houses in my area in hopes of figuring out how to estimate purchasing RE investment properties. Roughly speaking I've been practicing how to measure ROI's, Gross Rent Multiplier, and Cash on Cash returns. However I feel like there are some other important formulas I should be aware of when estimating the worth of a REI property. Any tips, websites, or formulas you all think I should look into when going through the process of figuring out the logistics of acquiring a REI property?

Thanks!