Gotta love texas (for flipping) as it is non disclosure.
I have found that if you are dealing with a typical home, in a typical neighborhood that zillow values are a very good guide. They compare square foot prices of solds, but don't take into account your fancy granite counters or dysfunctional floor plan for that matter and zestimates tend to skew the more unique a property is. If yours is the only one around that is on an acre for instance you won't see an accurate representation of value. Still very useful tool and all you have to do is look how high above or below the zestimates comparable homes are listed for to give you a good base to start with.
As far as forecasting values, never make a decision on this hearsay. R.E. historically appreciates about the same as inflation(3-5%), except when external drivers are in play. So make your deals work with current values and rents and if you get positive appreciation, count your blessings!