It might be a little challenging to practice the strange places as a DS/RC trigger, but I made a post a little while ago with some ideas about how to practice recognizing unfamiliar places as dream signs in reply to someone with a similar experience.
Might not be the easiest or most practice, but it might work?
Do you play video games? Because they can be quite immersive and often have you interacting with different/unfamiliar/new environments. If you can approach video games with that mindset and remember to do a RC while immersed in a video game envirionment it might work. It would probably be more effective that looking at photographs like I mentioned above and closer simulate the mindset you’d have to have in a dream to realize your unfamiliar envirionment is because you’re dreaming (because you’re usually immersed in dreams and kinda have to take a step above the plot/action to come to the realization that you’re dreaming, like you’d have to do if you were playing a video game and stopped to question your reality.)