You should certainly go see the commandante first, that is part of the main quest and not that difficult. Afterwards you need to go outside in any case.
The by far most important thing you should do before venturing into the forest is to get a new silver sword. Don't try to kill monsters with an iron sword, you will be at a huge disadvantage.
But you should be able to handle the monsters from the beginning of the chapter, once you got your silver sword. Remember that you can use bombs, traps, potions and blade oils. I've written about general combat tactics for our Gaming.SE blog, maybe that can help you a bit.