1. Investing into perk Hotter. 6 perk points give 3 Charisma in total.
2. Upgrading panties for Charisma, costs 5 soul crystals.
3. If you unlocked the witch cottage store, she has a Charisma charm that adds 1 point, it costs around 150 gold, possible to steal
4. You can buy or steal Lacy Panties in second town that give you Charisma, they cost 100 gold.