I would make it clear to players before the game begins that you're using TotM, because there are certain abilities that are much more useful when using a grid (such as the Mobile and Sentinel feats). If players don't design their character to optimize using the grid, it makes things a lot easier for everybody.
The biggest thing to making TotM work best is to reduce the number of combatants. While most people think D&D is best with a larger group (5+), TotM is better with 3-4 players. In addition, the DM should use smaller numbers of more powerful enemies, or turn a group of enemies into a swarm for mechanical convenience. The less you have to keep track of, the smoother everything should go.
In addition, you shouldn't fret the details. Movement and distance is whatever you want it to be, so don't try to keep exact figures in your mind. If you think something is within range, it is, and that's it. Sometimes player won't like your answers, but that's not really any different than being 5' short on the grid (a common annoyance IME). I'd keep the DMG rules for AoE targets handy, and use that with a dose of common sense as well.
The biggest thing to making TotM work best is to reduce the number of combatants. While most people think D&D is best with a larger group (5+), TotM is better with 3-4 players. In addition, the DM should use smaller numbers of more powerful enemies, or turn a group of enemies into a swarm for mechanical convenience. The less you have to keep track of, the smoother everything should go.
In addition, you shouldn't fret the details. Movement and distance is whatever you want it to be, so don't try to keep exact figures in your mind. If you think something is within range, it is, and that's it. Sometimes player won't like your answers, but that's not really any different than being 5' short on the grid (a common annoyance IME). I'd keep the DMG rules for AoE targets handy, and use that with a dose of common sense as well.