My method is usually to start with a series of mostly unrelated words. (The classic example is "correcthorsebatterystaple"). Then I replace some vowels with numbers or special characters. Using this example, I might do c0rr3cth0rseb@tterystaple. As you're still the only one here from your world, you have some leeway on "unrelated" - song lyrics or lines of poetry where you come from wouldn't be common phrases here. If you have non-Earth languages at your disposal, those are also good for coming up with things you can remember without writing down but still hard for a mind-controlled robot to brute-force.