Reddit mentions of Songcrafters' Coloring Book: The Essential Guide to Effective and Successful Songwriting

Established chord progressions can help, otherwise use chords + ears.

Theory is just theory, its more of a tool, however, it can help you understand other songs which may help you understand what you have in your head.

I would recommend reading about songs from a songwriter perspective. Not a technical guide. Well, they can help get quick patterns together, but more of the art.

For example Inside the art of songwriting is on my reading list. (although the cover is ridiculous). Songcrafters Colouring Book is an excellent book about taking your creative ideas / raw output and crafting in it into a better song.

As long as it sounds and feels good then it is good. Lyric writing has is nicely explained in songcrafting colouring book. Technical books I have read on lyric writing have been dire.

Try to establish a groove early on and work to that, that can help tie everything together.

Good luck.