lenpelletier says:
I wanted to get a map or some kind of visual aid drawn up to make things more clear but it just didn't happen this time. Things need to be crystal clear for all games, but especially for a beginner's game :) But hey, we're doing our best!
This might not work well with beginners, but in another game, we did a one-off with 20th-level characters. When it became impossible to keep track of what was going on in combat, the DM set up a map in Roll 20. We still described all our actions and rolled in GP, but we used Roll 20 for the battle mat and for players to be able to move their characters around. I don't know that it's necessary for the combats we've had so far (and I'm sure you don't have time to set up the field in another game system), but it might be something to keep in mind for later.
I think theater of the mind works okay here, despite some confusion over the workings of an area of effect spell. And, for the most part, it's worked out well in other, higher level games I've played. It's just that when trying to visualize combat with a 20th level character who could turn invisible, had 120' movement (with an upper potential of 360' in a round), and who could move around without taking opportunity attacks, it became impossible to theater of the mind that! Especially when your last turn in combat was 24 hours ago!
For our purposes, I think even a quick graphic done in Microsoft Paint would be sufficient.