Basically, have them incorporate my homebrew material (though playtested, of course).
The highlights would be:
Extra feat at 1st level, possibly sourced from race. A racial ability at 5th level, and again at 10th level, maybe 15th as well.
add a 1/2 to 3/4 arcane caster/martial class (Eldritch Knight less focused on martial and more on magic, Swordmage, Bladesinger, Arcane Archer and all those designs can hang off that class instead of fighter).
Sorcerer origin decoupled from subclass, similar to Warlock Patron/Subclass. More non-combat spells added to the sorcerer list so it doesn’t have to be a blaster all the time.
Warlock’s Eldritch Blast is a class feature, not a spell. Option to make it a melee weapon instead of a ranged attack.
Monk’s spell-like abilities aren’t fixed by level, but instead chosen from a list, like invocations. Also, give the monk martial art styles (like Mantis Style or Tiger Style) to allow customization of how they fight/defend themselves.
Hit point accumulation greatly slows at 10th level, or only gained every other level.
Remove excessive Concentration requirements from many Druid spells, such as Barkskin. Drop the “no metal” speech from the class.
Add back some additional weapon qualities (crit range & multiplier) to further differentiate weapons and reduced the “best weapon all the time” state of the weapon list.