1. Add a blowup/videlity device
2. Fit another graphics card
(2) is not really an option, unless you have a CT60 and are waiting for the Supervidel, or you can get your hands on an eclipse (which is difficult set up I heard). When Supervidel is released there will probably be a few eclipses come onto the market.
What I did was (1), I soldered a new crystal into the clock input for the screen, and this with Videlity allows you to set new resolutions. You either need to solder a new crystal inside, or you can get adapters that plug into the Falcons monitor and joystick ports.