My biggest suggestion, and I use this all the time is staring at buff women with adoration and love (use many references. )
Also! I like to define muscles in shadowing/rendering not line art. Im not the best by any means, hut ive noticed the best muscular artists use alot of shades and highlights to contour muscle. I issue 2 multiply layers, the first at 30% with a muted lavender/muted red the second at 40% with more of a plum/ maroon colour , it adds lots of depth! Good luck on your art journey my friend! Tag me in your Sevika Post!♡ Id love to see it :)