Completely stuck.

Hi, I just started Nightfall and I am on the quest where I have to get to level 12 or reach first spear. I completed all the quests I could find, and talking to the scouts next to the resurrection shrine no longer give me bounty. I'm totally lost as to what to do... except maybe grind to level 12 (level 8 atm). I think I'm missing something...

You probably missed some quests or didn't gain enough sunspear points via killing monsters. Check wiki for a list of quests in Istani.
I never had to grind my way off of istani though...

Have you explored 'Zehlon Reach' yet? You can grab some quests off towards the upper left of that area

No I haven't, thanks a lot!

Here is the wiki page for that primary quest http://wiki.guildwars.com/wiki/The_Honorable_General
Here is the sortable list of Nightfall Quests http://wiki.guildwars.com/wiki/List_of_Nightfall_quests

You need to do more side quests and collect bounties in more difficult areas, such as the Mehtani Keys and Issnur Isles.MY BAD. Too long since I started a character in NF.

They can not access Mehtani Keys nor Issnur Isles without first being First Spear, the First Spear requirement is what is needed in order to fight the General's men, which then leads to working with Melonni and subsequently heading into the Mehtani Keys/Isles area.

I have had this same problem on my characters, not enough quests that is. I managed to barely squeak out enough exp to hit level 10 without needing to grind on some monsters.

The quests that you run across marked "Master" aren't really difficult, or at least the evil Mime one isn't really difficult, and so you should give them a shot too.

This quest is possibly the one that ruins Nightfall, there is another one similiar when you get into the mainland, it isn't as bad, but these quests turn parts of NF into a grindfest.

Take a look at the quest links Darcy posted. In the end you may have to grind your way to level 12. Try keeping completed quests in your log and not accepting the reward until you are closer to level 12, this will allow you to earn more exp from kills.