I typically just go 12-14 CHA with Expertise in Deception and Pursuasion. This provides more than enough bonus to facilitate all speech skill checks that matter.
With such a low investment, it's still possible to max DEX and put a bunch of points into CON and/or another focus stat (Such as INT if making a magic focused AT/Wiz or WIS if you want to do something like Open Hand Monk)
