Hmm.Where to start.The truth of the matter is that every time is different.Sometimes it all comes out in a rush and you can blast a finished song out in a day.Sometimes it comes out in a trickle that you put down and keep at for however long it might take.For me I'm pretty happy if I can get the "mood" set right on a song first.By that I mean a progression or riff that evokes the emotion of the lyrics.On the lyric side of it,if I can get one verse down for structure,I know I can always go back to it and pull at that thread until it all comes out.To paraphrase someone else's quote about songwriting,(I think it was Bill Anderson's quote but can't remember for sure)songwriting is an art and a craft both.The burst of inspiration is the artistic part and the perspiration that comes about after the inspiration is the crafting of the song,and you have to be able to do both.I'm not all that young at 36,but have only been doing this for about 3 years now.