gianthold then the vale of twilight. you could also swap out the demon sands for gianthold if you want access to some epic content come cap, although youd probably level to cap more quickly going with gianthold.
with both of those, youll be able to get to level 20 fairly easily and it will give you 3 raids, 3 slayer areas, and access to greensteel crafting. plus the gainthold pre-raid (gianthold tor) is a good money making quest. each of the colored dragon scales sell for ~100k pp each, the whites for less and blues for more.
if you are on a budget, you dont really need to buy any lower level adventure packs as there is more than enough XP in all the f2p content to get you through the lower levels. having lower level adventure packs just speeds up how quickly you can level as you can cherry-pick all the high xp quests to run at each level.
id also direct you to check out this guide: http://forums.ddo.com/showthread.php?t=287854