Lots of good advise here already, but here is my 2p.
I often go out with my camera, just hoping to capture something. Some times it works, sometimes it doesnt, don't give up!
However, some of my best shots have came from planning. The shot below took a couple of days planning. I had seen this Pier a thousand times before, and tried shooting it many times but never quite got it right. So, I stopped and thought about it for a while. I realised that it had a bit of a story to tell, and lighting, positioning and time of day all had an influence. I had noticed the tide came in in a strange way leaving a little island of sand in the middle, which added interest to the foreground and the pier added a nice lead in line to the shot. I tried the shot using a normal exposure but it didnt look right, the sky tended to draw my attention away from the main subject... So, after checking the tide times online and waiting for a day with some wind to add cloud movement, I went back down later afternoon and tried a long exposure... Its one of my favorite shots, and I plan on having it printed and framed.
However, not everything can be planned, and the stick stuck in the sand in the water was a fluke and had not been there on previous trips out, but adds something extra to the shot. So ,remember planning is not always everything!
Stick It by
dankellys, on Flickr