I have a few friends that write EVERYDAY. No matter what - they NEED to put down some ideas, or the day is a wash. Some finished songs are actually "pieces" of many other little tid-bits that began as short ideas. Whatever way you do it - just don't ever discard anything, and try to record as much as possible.... even if it's just a small, handheld mini-casssette. I used to keep one in my car to get the latest songs from the radio when I was playing the top 40. It really helped to have that "edge" with repertoire. I taped the Elton John song, the day that Princess Di was buried, quickly printed the lyrics and performed the song that evening. (Luckally, I knew the music from the original song) Staying on top of the craft has many rewards, so use any suggesstions that help you create a "flow".
There are NO right order - words, chords, tune ..... just do it YOUR way, and it'll happen. Find something that works, and fine tune it. Customize it, and personalize it. It'll serve you well.
BTW - I can no longer play EITHER version of "Candle in the wind" with out mixing up the lyrics. I played it one way for 15 years, and another for 5 or 6 .... now I'm ALL messed up.
....Norma Jean....England's Rose ..... AAAGHHHH !!!!!!!!!!