Song production

[Fasttracker]

How do you guys go about making a song?
When i try to make a song i usually don't get further then a loop.

I start to play with some sounds loaded in my mpc on a 4 bar loop , lay down a beat or some melody , add some bass sounds , some fx sounds , add some hi's and stuff till i get my groove going , but then , if everything sounds right , all adjusted/tuned and stuff .i suddenly lose my inspiration, i kinda get stuck after making my groove/loop , so all i'm left with is a really cool 4 bar loop.
When i then try to make a track ,i get a really lame song with lame transitions/breakdowns and stuff.
Okok i had some luck on some songs that seemed to just write themselves as i was playing , just totally in the groove ,focussed as if i totally emerged in the song , ( a sudden overload of creativity i guess) but most of the times i get stuck with a loop.
I have tons of loops just waiting to be stretched out into a song.
There are also a lot of times where i just make track and find some technical malfunction , then i get totally focussed on that malfunction trying to repair it , forgetting all about my song and when it's fixed i totally lost the feeling of the moment. But that's remedied by just bypassing the malfunction , writing it down and fixing it some other time as to not loose your creative surge.

But anyways , back to the question , how do you guys go about laying down/producing a song?

Greetz...