Do what PawPaw said.
I live just north of Dallas near 75 and go thru it frequently. After 9 am and before 4 pm follow 75 to downtown Dallas. Approaching downtown 75 will become I-45 toward Houston. Follow i-45 south to I-20. West on I-20 to I-35E. South on I-35E. That route will have the best roads, easiest highway transfers, and lesser traffic.
Stay off of I-635. And don't try to transfer from 75 to I-35E in the downtown area. Lots of construction in the I-35E/I-30 area downtown. And I-35E just south of downtown has narrow lanes with curves you really have to be careful on. Going straight down to I-20 avoids all that.