For leveling the doll what I did was I went up to Fort Charles and attuned one or two of the vets/sergeants and ran around in big circles until they were dead. It might be time consuming, but it works.
I would stick to staying around Tortuga and Port Royal until your a bit higher, also having a healer is a blessing too if your taking on enemies higher than you.
I'm level thirty and 95% done with the black pearl quest so I'm spending a lot of time training my weapons and its quite boring, so doing it early is probably the best way to go.
Good luck to you.
