Techniques for maintaining the course of the plot

Do I have any techniques for maintaining the course of my plot?

In a word NO. I start out with a rough idea of a story, but it's not until I start typing that the plot starts to evolve. Sometimes I don't even have much of an idea of what I am going to write but I start tapping the keys and 4000 words later I have taken my characters down a path I didn't even knew existed a couple of hours before.

I sometimes wonder if it because I am a new writer and have lots of ideas in my head. So far I have been lucky and writer's block has not been an issue for me.

Bits and pieces of the plot come to me at all times of the day and night, so I make sure to keep a note pad and pen handy at all times. I may just scribble down a sentence but when I get home and open up my laptop, that one sentence can easily lead me to finish a chapter in one sitting.

I really don't have any techniques when I write. I am learning things through reading WD magazine and joining online forums, but I have no professional training, I just write because I enjoy it, and I get so excited when the story progresses, makes sense, and is enjoyable to read.