When I first started AST I kept a little note next to me to remind me what each card did and what each royal road did. It didn't take too long to just remember them all.

Basically:
Enhanced Set
Balance - Damage up
Bole - Defense up

Extended Set
Spear - Cooldown reduction
Arrow - Speed up

Expanded Set
Ewer - Refresh MP
Spire - Regain TP

Enhanced = +50% effect
Extended = +100% duration
Expanded = -50% effect, effect is AoE