Well first you just dun gotta want it that bad.
Second it helps to be immersed in music daily.
Third it helps to have time to yourself, divorce/separation works there but it may not work if you engineer the separation first - it is all about mindspace -- redundancy, divorce, bereavement they all leave a hole in your attention and then you can fill it with a song..
Fourth it helps to know the audience (not personally but by genre).
Fifth - there ain't no rule that says you have to go public on any song especially the first - imagine a guitarist going public after a week's learning (or a month) - no! Practice applied to any sport improves the breed.
Sixth - I would advise investing in a rhyming dictionary - a good one like the Penguin one, a thesaurus and a good dictionary because you never know when the word you "knew" turns out to have conotations or a different meaning! I use the SOED CD ROM because it has a rhyming function based purely on sound anywhere in the word - contained rhymes can be fun (see Cole Porter & also enjambed rhyme). Dictionaries are not the B all and End all - they are a resource, a prop, and sometimes you may need them. And PC based versions are quicker, if less portable.
7 the Golden Rule (as GBS said) is that there is no Golden Rule. However there are many things that sit very awkwardly in a given context. And some that work because they flaut the expected norm, especially humour.
8 Never rely on memory - if you see, hear think of something - record it there and then, come back to it when you have the mindspace.
9 And if you contact me via PM or via cresby.com I do have a CD of a book written by myself that is all about being creative - mostly allied to wordsmiths. I would recommend it highly if I wasn't so modest.