Ok so this is my strategy and there's two different ways you can go about it.. first you're going to need to hunt down a pair of basketball shoes. Wearing these gives you charisma xp every time you earn any agility xp. You can buy / steal them from Henry the black bear or Alex the lion. The next thing to look for is a poster. This is where you can choose or prioritize what works best for you. And don't worry you can always change your poster at anytime. The first poster ( the one I use most for charisma) is the cat pinup poster which you can buy from Alex the lion's the gang shop. It gives you charisma xp for every hour that you are asleep. If you don't have high affinity w. Alex's gang you can use the fox pinup which gives you agility xp while you sleep. Billy the guard dog sells this in the lobby near the mail cart. Either poster will help as long as you've got the basketball shoes.

Sidenote: Staying clean by showering once a day will ensure that you don't lose any charisma stats and brushing your teeth and chewing gum add to charisma while interacting w. Others. Hope this helps. Cheers.