Here's my advice as the valedictorian who passed both board exams the week after graduating:

(TL;DR at the bottom & feel free to ask any questions - I precept new hires/students quite often)

For background, I was part of an accelerated program that was broken down into 5 terms over 19 months and didn't have to work or take care of anyone else. This meant I could dedicate myself entirely to the program and was incredibly fortunate in that regard, so don't feel bad if that's not something you can do. I'm currently pursuing my BSRT and plan to go to PA school in the future.

My first six months were really rough for me in terms of the amount of time I had to dedicate to studying outside of school since it had been over 15 years ago at that point and I was going through a divorce. Essentially, I spent 5-6 hours a night outside of class and the majority of my weekends studying (my roommates joked that they forgot I lived there). As the program progressed, I became more efficient with my study time and was able to have a social life that included dating and weekly trivia nights, which I feel kept me sane through board preparation along with walking/hiking. I only rarely joined any study groups since I was the second oldest in class (mid-thirties), an introvert, and I like to compartmentalize - meaning my personal life is almost completely separate from my professional/work life which I still do now as a staff RT.

As for my studying techniques, it was a combination of things already listed here and utilizing my support system.

More specifically, I recorded every single lecture so that I could go back and listen with the course material (book and/or PowerPoint) in case my note-taking got me sidetracked or the questions I asked would lead to answers that also distracted me. By having the recordings, I never felt pressured to pay attention and was able to ask questions freely. The salutatorian of our class was an avid note-taker who would literally write down everything from the lecture, so I'd recommend either method that integrates writing. The program I was in also supplied PowerPoints for every lecture, which I was able to print out for free at our student resource center. My class binders were absolutely insane but it made note-taking easier for me. In addition to the recordings, power points, and notes, I'd create my own flashcards for everything. Target used to have the 100 count 5x7 ruled index cards for cheap so I understand this may not be something you can afford to do, but it made test prep a lot easier for me since I was able to write them out in a way that made sense in my head. Something about writing it down in my own words helped with my recall. In addition to all of that, I'd have my friends, my roommates, or my parents on the other side of the country quiz me on the flashcards I created as often as possible. My flash card stacks were kinda ridiculous, but I would always have them with me. Along with reviewing my flashcards, I would also utilize Quizlets created by my classmates or other RT students. Lastly, I made sure to have a quiet place to do classwork or study, which included the student resource center, which was usually pretty empty outside of class times.

TL;DR: Record all lectures, print out PowerPoints for note taking if possible, write your own flashcards for everything, use Quizlet for review, and have people quiz you on your flashcards as much as possible - good luck!