At lvl 12 you will likely be transitioning between wherever you started and the town of Bree. So, if you started as an elf or dwarf, you will have moved through Erud Luin after beginning in Celondim (as an elf) or Thorin's Gate (as a dwarf).
If you rolled a hobbit, the Shire will have kept you busy until at least lvl 12 but the quests will now be getting thin and you may already be yearning to head for the bright lights of the big city.
And finally, if you rolled up a man, you will have spent your formative years in Archet before moving on to Combe, Staddle and the Chetwood and in fact, may already be in Bree!
In any case, The Brandy Hills, the Fields of Bree, (Southern and then Northern), The Old Forest and the Barrow Downs are the next places you will want to explore and fortunately for you, they all lay just outside the West Gate of Bree Town.
When you are done with the areas surrounding Bree, it will be time to head south for the Lone Lands, but that day is not today!
In the meantime, "Have fun storming the castle"!