Stat Buffs only, or Feats?
Regular Human, or Variant Human?
Rolled Dice, or Point Buy?
Paranoid against DM nastiness, or So long as you don't say "monty haul" everythings good?
The simple and easy choice is to use the stuff the PHB already has for it's Quick Build. Cha your max stats, with +2 Cha stat bump at level 4 and level 8.