As some previous posts indicated, it takes a bit of time to get used to the visual perspective of taxing high and long aircraft. I find taxiing the 777-300 easier than some of the smaller planes I have flown. You just have to be a bit more vigilant, monitor you taxi speeds, consider your momentum, go fairly deep on the 90 degree turns, and use caution with the thrust.
Rarely do I use differential braking, use of the tiller is great below 30 kts (not a limitation) and rudder above those speeds on landing or takeoff. As far as 180 degree min. radius turns on a narrow runway, main gear next to the runway edge as close as possible, full tiller deflection, full braking on inside truck, sufficient thrust on the outside engine to get it moving. Hopefully you won't have to do many of those!!