Play time.

[BeepBeep]

I am usually only able to play 3 to 4 hours after work on the weekdays, and rarely on the weekends if i'm not doing anything. I'm not able to level up as fast as some of the other hardcore players, but so far I have found it to be reasonable enough to stay interested in the game.

With limited time I do recommend you try a solo class (i.e. Necro, mage, druid) because some nights there won't be any available groups and then you can go straight to soloing while waiting for a group etc..