1st or 3rd???
There is a lot of thoughtfulness that goes into creating a book series, however, there is no way to plan every detail before the first book is written. Tweaking will occur. In fact, every book is an opportunity to make the reader's experience more satisfying than the last.
One thing though, that probably ought not to change is the perspective of the story teller.
Vanessa paced the jagged remnants of the growhouse methodically. The police tape was gone, evidence collected, pictures taken, but the atmosphere remained thick with atomized cinderblock and wood. The scent conjured up latent memories of a typical Missouri '80s childhood, quarries and campsites, now perverted with the days violent destruction.
I paced the jagged remnants of the growhouse methodically. The police tape was gone, evidence collected, pictures taken, but the atmosphere remained thick with atomized cinderblock and wood. The scent conjured up latent childhood memories; my friends and I skirting the edges of a limestone quarry, the wet ash of damp campsites, layered with gravel and fallen oak leaves, these memories now perverted with the day's violent destruction.
First or third person storytelling helps to set the tone of the story. First person is intimate, but the reader only knows as much as the narrator. The story unfolds for everyone at the same time and creates a sense of solidarity between the main character and the reader. Third person allows the reader to see the story unfold from above, almost omnipotent. I lean towards first person because I want my reader to feel like a partner with my main character. I hope it's the right decision.