For me, one of the key advantages of writing for a visual novel compared to a more traditional story is the more intimate connection to the main character's thoughts, as they flow seamlessly along with the narration and dialogue. I suppose that could also be said for writing from a first person perspective in general, of course, but I think it's important to use that to your advantage.
There's a fair balance to strike, too, as you don't want to get bogged down too much in a character's inner thoughts, but at the same time, if you just gloss over them and blaze through a scene it can often feel lacking. Since for me, the main character is a character in themselves and it's important to explore why they do what they do, and how they feel about any given situation, and aren't just a blank slate for the player to slot into.
That's my approach of course, and plenty of visual novels do things differently, with some not even being written in a first person perspective, or even having narration at all. (Being purely dialogue based instead) So there's no one 'right' way to approach it, of course, and it should come down to what you think your project will mesh with the best.
Also something to consider about a visual novel is the 'visual' component--which is one of the largest differences from say, a traditional novel. Because when you have visual aids for the likes of backgrounds, characters, etc. you can often plan your writing around this and avoid redundancy in the narration if what you're describing is already clearly in front of you.