Well as far as writing there are basic rules but the main one is that There are no rules, you are a creator God is using you to get a message out. when people come to me with lyrics with out music, its most of the time in some kind of rythm but not totally. as a producer\ musician, I take what they have and play out chords ruff draft which then gives us some sort of feel\flavor. if this is what the writer is looking for then we go with it, and add around it. Some times you can use other songs to map the feel\flavor your lookin for....I hope this helps also: sing it on out and record it on something so that you dont forget it....
It can be tedious with trying to ryme and think of lyrics sometimes, it comes to you fast and sometimes you have to put the pad down for a while and something will hit you in the middle of the night (as a writer, you got to get up and write it down cuz chances are you wont remember it in the morning.......sometimes you get the hook first some times you get the verses there is no wrong way what ever motivates you plus staying in the word.... I ran my mouth enough I'll holla