Well when following the main quest one leads to the next. If you have zero quests in your quest book and your quest helper is turned on but is not pointing you towards your next objective you might want to open a help ticket. This happened to me once in Wizard101 and as it turns out I did decline a quest. I had to search everywhere for it and when I found it I was able to progress from there. And yes you should never decline a quest.
Wicked Erin, Self Appointed Unlimited Class World Swashbuckling Champion Supreme