Any guidelines to consider while deciding the voice of your narrative, i.e whether it should be a first-person account, or should the story be narrated by the voice of an omnipresent storyteller?
The voice of the story is what makes all the difference. But how do you actually decide between the two?
Depends on what purpose you're trying to achieve. If you're exploring one particular character and intend to experiment with viewing things through the lens of another person, first-person POV or third-person closed.
Third person omnipresent comes from a story where there's less focus on one character and more on an ensemble, and the tension doesn't come from an ambiguity of a certain characters' actions but rather the overarching plot.
I would say that closed, POV-based narratives are for intimate, character-driven work, while omnipresent/omniscient narrators are for plot-based work.
Please take my words with a grain of salt; after all, there are plenty of exceptions to this.
There are other narrative styles as well as the two you have suggested but that is neither here nor there when it comes to answering your question. Unfortunately I can't really give you a definitive answer as to how one picks a particular narrative style for a given tale. I work largely with found stories, I create universes in a relatively arbitrary level of detail and then tell the story(s) of everyday characters from that setting. When it comes to choosing a narrative style it usually picks itself. I use a lot of first person and first person peripheral but some stories are better told from a third person POV, especially when none of the characters are particularly important (either within the universe as a whole or to the story being told).
When it comes to understanding the effectiveness of a given style for the story you are telling you need to consider the interaction between the characters and the reader. In particular how does the POV you are using portray the characters to the reader and what does that show the reader about the world? If the character and world portrait created is what you want to communicate then you are using an appropriate style. This does not make it the only style that could be used though.
