To go with this, a list of low level sponts the characters can cast that may be relevant to the adventure is useful. As the SG you have an idea what is coming up, so you could easily have a few sponts pre-prepared to talk the new players through.
Also having them pre-prepared, so you have a quick answer is useful. When a player with a Rego based magi says "I control things, can I move the log", it's much better to look at your notes and say, "It is a large log. It has 2 level of size modifier. A touch range spell to momentarily move a decent size branch is level 4. The plus 2, means it goes to 5, then 10. Anything after 5, plus 1 is +5 level. That would be level 10. You can't get to 50 with no fatigue, however, with a d10 you could put in some extra energy (get a fatigue level) to have the spell be more effective." Also, if they just miss, you could bring in the concept of confidence.
I tried to find an old thread with low level not fatiguing sponts, however, it evaded me. There is this thread.