Where is home?
City centre? Rural? Coastal?
I live in a populated city, and I don't have easy access to a clear horizon.
That makes it somewhat harder. I personally really like the horizon tests, but those are kind of out.
You can do all the astronomical observations... size of sun/moon, angle of sun/moon, rates of motion, etc.
You can coordinate with someone else to do the triangulation types of observations.
Are you in the Northern or Southern hemisphere? Can you observe the stars in the Southern sky?
The main issue with all of these astronomical observations is that many flat Earthers don't put any stock in anything that happens in the sky. To that, I offer the same wisdom that the whole 20 tests video is based on: "You need to decide what model you want to test, and then you can test it." So if you believe the size of the Moon means nothing to the shape of the Earth, just skip over that one. If you think the horizon always rises to eye level, then you should test that. (Sadly you can't test that one I guess.)
There are the satellite tests. Again, that's relevant if you believe that satellites shouldn't be part of your FE model.
The one that anyone can do from anywhere is to make your own flat earth map based on publicly available flight information.
To summarize, I would start with what you suspect the world is like and test that. If you think the Earth cannot be spinning, then do a test based on the rotation of the Earth. If you think air pressure can't exist next to space, do a test based on air pressure, etc.