I have been playing the game for a couple of days and I must admit that it is quite fun and well done in lot of aspects, I am quite impressed. But there is one thing that I still don't understand well, maybe due to trying to find in the secret world the same themepark progression as the rest of the mmorpgs out there hehe.  So, how do you know you have "ended" a zone? I have been playing a couple days and now I am at tier 10 of the story quest so they sent me to savage coast, but I have tons of quests I haven't done, and not only main quests, also side quests that must be out there waiting for me to find them... I love that aspect of the game, but it also makes me nervous as I think I am not playing the game well but if I see I can go to other zone where the story quest sent me, and kill the mobs there without dying and I am going to get better gear there, what is the point of going back to the previous zone (kingsmouth) and what is the poing of having so many (MANY) quests there that won't be done?

I would like to hear the experience of players that played some time to the game and know how the progression is thought in the game please!

That really depends on how you want to play.

If you manage the main quests fights without a prob you prolly will be able to get stuff done in the next zone and could move on.

I for example always try to do all quests i can finds before i even start the mainquest in an Area i love the quests and storys and how they tell you the story of the zone you are in.

I want to know whats exactly going on in the zone and for that you should at least do all brown and investigation quests but like i said if you are only concern about progression you can prolly advance to the next area if the Mainquest battles were easy for you.

In later zones the game gets way tougher so you might end up spending more time there anyway.

Those are both good pieces of advice.  You'll know soon enough whether the mobs are too tough for you, and it's always fine to go back to the previous zone and do more.  Going through a dungeon run can also result in some nice gear that will help you in the next zone -- Polaris is an excellent dungeon.  Also, don't get too attached to your current ability wheel build.  You will at various times need to switch out some abilties and use a different deck -- you'll definitely notice that in the Blue Mountains, and that is usually the first zone where things get challenging.

That all said, it's the story quest that opens up the new zone, so once you have completed that, it will invite you on to the new zone.

Like others have said, you can go whenever you are "ready" to take on the mobs there. 

I usually just follow my main story quest and leave my current zone when the quests become "easy" there. The quests in the new zone should be "normal." Transylvania is "normal" at the beginning, but then after the first starter areas, they seem to all be "hard" but doable solo when I had all QL10 greens.

EDIT: I guess me and Ortwig were writing our answers at the same time.

Did no one really mention the achievements section??

The main missions are listed there for every zone.

I usually move on when I have completed all the missions, got my clothing reward and find no more sidequests which I haven't done before.

The missions are mostly brilliant and I don't want to miss even a single side mission.

Originally posted by PWN_FACE

Like others have said, you can go whenever you are "ready" to take on the mobs there.

You don't even have to ready for the mobs to go check out the other zones, you just have to be sneaky/fast. "The Meowling" hit when I was hardly halfway through Kingsmouth, but I managed to complete it over in Blue Mountain with only 2-3 deaths. But then Superstorm Sandy shut me down for a week and I missed my shot at "Crossing the Black Path".