It would be enough, if there would be "training missions" (maybe like guildheists) for every class. With different difficulties so that you can improve yourself.

Some way like this:
For Tanks: 1. Rotation-Training (dps/emnity-check) 2. CD-Rotation-Training 3. Both
For healers: 1. Heal-Training (HPS-Check) 2. Healer/Emnity-Check (No-Overheal-check) 3. DPS+Heal-Check
For DPS: 1. Rotation-Training (single-target) 2. Rotation-Training (multi-target) 3. Rotation-Training (both) with AoE-dodging

At the end you get a rank.. D, C, B, A or S and a nice title.