A Party template is the basic reason for a group of people to be together with a motivation to get involved. It is a template that the Keeper controls, and that the players pick an character type from which they generate.
Here are a couple of templates. 

The Gumshoes:  Two private investigators, thier secretary, and an old war buddy.

The Papal Investigators: A Bishop and three priests ordained for the pusuit of the unusual and evil.

The Police Dept: One or two detectives (if two, most likely with completely conflicting personalities), an ordinary constable (the combat guy), a forensic scientist. Recurring NPCs include informers, a bureaucratic police chief, ex-cons etc.

The Class of '26: One or more professors and their students (modern students allow for a HUGE range of unusual hobby skills). Or a group of graduate students after their professor is killed followed by one of their classmates after a few days. Or the faculty at Arkham High School after a spate of mysterious student or teacher deaths. All disciplines the PE teacher could be a WWI army vet! Perhaps the drama teacher found a copy of an obscure play about a King In Yellow and decided it would make a great spring play.

Gentlemen's Club: Members of a local Masonic Lodge. IIRC they were quite popular in the 1920's.

Newspaper: Jounalist, Photographer, and cub reporter, Add in an editor and/or sub-editor. 

Typing Pool: Each individual receives a page of what looks like incomprehensible gibberish. That day at the water cooler each discusses what nonsense he or she just typed. An NPC overhears them and suggests some sort of sinister nature about the materials and how it happened once at another company in another state. That NPC doesn't show up to work the next day and the Boss begins scheduling suspicious one-on-one interviews with each employee about the Gibberish Document.
Motivation: keep their jobs, keep their lives, save the lives of their coworkers. (I can't help but think of the X-Files episode "Folie à Deux" in which a man working at a phone bank believes his boss is a monster that can "hide in the light" and turns people into mindless drone "zombies")

Clippings Agency Workers: Not really sure what that is, but if it is what I think it is, perhaps the above scenario works well also. Instead of typing gibberish, they're clipping it. Or perhaps they clip an article that somehow ties together a series of previous unrelated crimes that hit too close to home to report to the police. Motivation: similar to typing pool, add interest in finding obscure news

Poker Players: Just because they meet regularly on Thursday night to play poker doesn't mean the adventure has to start there. Jeff calls the other guys to help him move into his new house. Only it turns out that the place is haunted by the spirit of one W. Corbitt. Simple enough. Or perhaps Jeff brings in some strange item he's inherited from his late great grandfather.
Motivation: loyalty to friends, honor (in gaming and life), Man Rules (haha), personality's, one-ups-manship, hero complex, everyday people motivations, too much curiosity, etc.

Factory Employees: The beloved foreman disappears suddenly. The owner spreads rumor of a scandal, but no one believes them. Or, The power goes out in the neighborhood, but the factory keeps running, things get more bizarre: something lives in the machines.
Motivation: keep their jobs, maintain productivity, loyalty to friends/foreman, desperation (poor factory workers who can't afford to be layed off or fire or try to find another job)