Character Advancement
From Unusual Haunts
Characters don't advance by gaining extra activities (there's no more time in the week!), but they can improve in other ways.
Activity Improvement
Investing resources found over the Bridge in to the class of your choice can improve what it teaches. This will be a slow and gradual process though.
Poisoins
It's known that more exotic ingredients fed to a Poison will cause it to have more powerful effects. Those that attend Evan Jones' workshop can particularly benefit from this.
Rites
Rites are mixed bags, allowing you to "sharpen" your ghost. What is known is that Rites always involve giving something up to gain something, but can allow you to become more specialised.
Haruspicy
The backing of a good ancestor can give you extra abilities. If you can reshape your family tree via Haruspicy to fit them in.