Well, there are two ways to approach that. Sure, you can do the things everyone does or you can try to do things you don't see as often. There are a couple of reasons to pick a location.
Probability: People spend huge chunks of their lives at Home, Work, or School depending on situation. So it makes sense to have scenes there.
Social: Places outside of those mentioned above where people would be together. Any sort of entertainment, necessity, or hobby. This is clubs, restaurants, stores, or gyms. Things like that.
Nudity (or more revealing): These are places where people don't wear normal clothes or take their clothes off for some reason. Such as the clothing store, pool, or doctor's office. Basically, it can give you a reason to put a character in sexy clothes or no clothes.
Story: Yeah, some h-games have them. This would be a location that's important to the story. This is highly variable but could be places like a scientific lab, police station (for non-police because that's just work), cabin in the woods, etc.
If it were me, I'd start with the story or at least the theme of the game. The locations should naturally come from there. If it's something like a dating sim, then you can kind of go wherever you want that makes sense for a date.