Best Way to Book as First Timer?

Hello! I'm looking to book my first cruise with a friend. What is the best bet for getting a good deal as a first time Virgin cruiser?

--Should I book directly now, through a travel advisor, etc.? --Is their Black Friday sale the best they typically have? --How far in advance should I book to get the best rates?

I've been on a couple cruises in my life -- once with a friend's family back in the early 2000s on a Celebrity ship, and once with my family for an Alaskan cruise with Princess pre-COVID -- but have never been the one doing the booking.

Thanks for any and all advice!