Different artist have different processes. Work on what you like more first and figure out how to fit them together. Or vice versa if you prefer. Just get something recorded then you can tweak it further. Record as much as you can even bits and pieces. You can work things together or expand on what you have later. Jimi Hendrix has more posthumous albums than when he was alive. He recorded almost every moment of studio time. Many of those outtakes were later fleshed out with studio musicians and released.