How do you prepare for a recording session when you're unfamiliar with the artist's work or genre?

I love talking with my clients especially with new ones because I can always learn something new from their inputs: I listen to the track received and, based on the client's references, my inspirations and my listening experience, I look for the suited sounds through my instruments and microphones positions.

It is all about the song. If you don't know the artist you are working for and don't have access to their previous bodies of work, then I just do what I can that best serves the song and rely on instincts. 

To prepare for a recording session with an unfamiliar artist or genre:

Research: Listen to their music, watch performances, and read about their style.

Practice: Play along to their music and experiment with different techniques.

Collaborate: Communicate with the artist and producer, and be open to feedback.

Adapt: Be flexible and willing to adjust your playing to fit the musical context.

Just listen ans try ti capture the juice of it than i always put my personal style into things cause i think that this is what you will get from a session musician, his style into the tune.

Listen to the artists previous work and ask for reference tracks – these will give you the general vibe to look for.

But I don't spend too much time listening to these. My personal approach is to not try to nail the exact style/sound of the genre, instead I do a fusion of my own style and the artists style/the genre in question. This way I add something new to the mix and I always get a lot of good feedback when doing this.

When preparing for a recording session with an unfamiliar artist or genre, I immerse myself in their work by listening to their previous recordings and studying the genre’s characteristics. I focus on understanding the mood, tone, and key elements that define their style. Additionally, I stay open to feedback during the session, ensuring that my contributions align with the artist’s expectations.

Listen to reference tracks, reverse engineer things like the "duty" of my instrument within the genre, or arrangement, understand the tone and closely replicate it, then work on the arrangement until I can play it in my sleep. 

Its a lot easier if you're replacing an outgoing member, but if this is a new band then it will take some back and forth until a good equilibrium is reached.