I have not really seen a thread (maybe I overlooked) about leveling and progression. Basically the best way to level is to do quests that are close to your level (yellow) and as many as possible. The leveling is setup so that you cannot grab the cuirass/robe tails of your lvl++ friend and power level.
If you complete lvl 30 quest/dungeon at lvl 20 you get a significantly reduced exp and apparently forever lose that exp.
If you leave Glenumbra (into Stormhaven specifically) with less than 93 quests (what I personally had) completed then you missed some, though cannot put into terms of too fast too slow. Try to complete requests before they go stale (turn green) and do not complete if Orange. We did an experiment with a guild mate at 20 in an area of 30, we got ~1000 exp for complete, he got ~100. Another guild mate in a hurry had to grind out 48 and 49 (before they let non-vets into vet overworld).
The reason I mention it as some do not seem to get it. Probably too late since they decided to let non-vets into vet ow (i believe is one of the worst decisions made thus far) because the event that allows the transition could probably be done at lvl 45.
Gunerm Cleric ~ Dragon Knight, Tank ~ vr14
Cruleg Nimec ~ Dragon Knight, DPS ~ vr14
Gunem Cleric ~ Templar, Heals ~ vr3
Cleric Gunem ~ Sorcerer, TBD ~ vr1
Daggerfall Covenant (only) ~ NA
Daggerfall Cosa Nostra ~ Founder ~ DCN ~ DC guild leaders only (no cross faction PvP guilds)