I was going to talk about music theory, which of course plays a part whether you acknowledge that or not but I think I'll try to simplify what I do. There are two different approaches for me: a song might start with an emotion. Often a strong emotion and I then look for an appropriate chord sequence to add an emotional melody to. The choice of notes for the melody is in my opinion, something that can't be taught. You've simply got to call upon all of your life experiences, both the fantastic moments and worst, most painful of your experiences and memories. It might sound pretentious but when you think of melody like that, it really does have the ability to speak about exactly what you have lived through. This is something that I instinctively do in my productions - I feel the emotion of what I am playing regardless of the instrument, apart from drums. The marriage of words to the vocal melody should be seamless - I try to write something that I believe I can't improve. To my mind, whatever I write is as good as I can possibly make it and I'm never disappointed with my work other than not having the range to hit certain notes that I instinctively hear in my head - I don't want to sounds arrogant here but surely that's got to be your goal as a songwriter! That all applies for the songs that I write from personal experience. If I write something about for example a fictional story about a Hollywood leading man as I did in a song called 'leading Man' which Dutchbeat made a wonderful video for, it's exactly the same as above, call upon all of your emotion and experiences to bring a part of you to that song. Obviously I've never been a Hollywood leading Man but there is always an angle to project a part of you into that song - something that I firmly believe in! There are many tricks and skills that you pick up along the way but that is the essence of how I write! 
That's a fantastic approach to songwriting, Paul, exactly how it should be!
There are good songs, and then there are those songs that get under your skin and make you feel exactly like the artist did when they wrote the song - or at least your interpretation of that feeling. And those are the ones that really stick with you!
For me it's all very random, I've never sat down with the intent to write a song now.
Every now and then when I'm playing around with an instrument I suddenly stumble across something that I like, that could be a guitar riff, or a couple of chords on the piano, or even something I've just programmed on my drum plugin. Then I think, this could go well with a certain melody on another instrument, and start playing around with that... etc.
The writing and arranging parts are kind of the same for my songwriting process. Unfortunately this means that I usually 'write' in the DAW, and am rather useless when not around my computer.
Hi, i recognize that thing that if not really happens in the first 15 minutes, it is not going to happen
nothing real good anyway...
i may continue, with that i aid of a truckload of samples and machinery...and even have fun with that
I do that as well, there are too many unfinished projects on my computer that I'm sure will never go anywhere, but occasionally I revisit them and play around with some settings and sounds just for the fun of it