Location shoots in public parks and hiking locations are simple enough. You show up with your clients or group on an ideal day at the planned time and start shooting (Barring any public events being held of course). It's when your ideal location is on property managed by town government, a religious group or a private business that it can get a little tricky.
These are places of business or worship and they host a variety of events on their own. You will need to call ahead and see if they are okay with you showing up with clientelle for a shoot.
Historical Sites
Historical sites are usually managed by the town's historical society, or a board of trustees. And they usually require some sort of donation or fee to use the site. Sometimes, depending on the size of the meetup or the length of the shoot you can get inside for free.
These sites do host events like field trips and the odd wedding or two, so communicating with the property manager is key to making sure you (or anyone using the property) are undisturbed.
Religious Buildings
Old Catholic churches, Mosques and other buildings of worship are beautiful in and of themselves. Outside of their usual worship times, they are used for weddings, funerals, and other community events. Sadly this means you can't just pop by without prior notice.
Another thing to keep in mind are the virtues and practices of these groups. Photographing lewd or demonic characters at a religious location is probably a bad idea.
If you don't have an "in" in the group or community that owns or manages the location. You may get shot down, if not immediately, then after they've given tentative consent.
This happened to me once. A week before the shoot I got an email apologizing for the last minute notice, but the leaders of the church changed their minds and weren't comfortable with the cosplay shoot we wanted to do. (Final Fantasy VII characters) It was disappointing but not super surprising.
Privately Owned Businesses
This one's pretty much a no brainer. to shoot at a business, you'll probably need to rent the space. But there may or may not be additional criteria required to discuss rental. They will want to know: how many people, will there be food, what area exactly are you looking to shoot in... Etc. So be prepared to answer questions with as much detail as you can.
On the off chance that you're location is an especially charming office building, or public shopping center, you may be able to get away with just contacting the owners of the building directly and getting the okay to shoot so long as you don't disturb any of the locale's business.
Potential Financial Requirements:
Space rental: If it's owned by a private business or religious group you may need to rent the space for an hour or two.
Donations or Fees: Most historical societies will agree to let you use the space if you donate money. The donation will likely be put towards helping to maintain the building. Or they may charge you a fee to use it for a larger group.
Event Insurance: Is a kind of insurance that helps protect you, the event planner, from a variety of mishaps in several specific areas of focus. Super handy so you won't be sued for someone slipping on the grounds, or if something breaks.
Tips:
Call ahead: Even public parks are used for private events. Make sure you won't be crashing anything.
Scout out the location before the shoot: You can usually walk through the space with the owner or manager if it is a historical site or private business. This allows you to really see what space you will be working with and better familiarize the owner or manager with what you will be doing.
Know the number (or estimated number) of attendees: If you are hosting a meetup or gathering this can be hard. But depending on the location, And who owns and manages the space, they may need you to get event insurance.
Respect the locale: Its important to show respect to the owners/managers. Be open and honest with them and be prepared to instruct your clientele/photography subjects to do the same. Especially if you want to be allowed back.
Watch the weather and plan for the season: You want to have, at the very least, a loose backup plan (or date) in case you get rained out.
TLDR: Don't be a douche, Ask before you shoot.