More than any other game, fate system lets you re-tool characters on the fly. (Skill-point rearrangements, changing aspects, ect). So, don't throw out good character concepts that are poorly designed because everyone is new to the system. Instead, just overhaul the character sheet, and the character can just say "I worked to improve this" or "I don't do that anymore."
Because this game is so, so character driven (more than other games, where characters can be driven by their stats or abilities), coming up with a kicking character is way more vital than choosing which evocation elements you want. Put your efforts towards helping your players focus on character concept and backgrounds.
