Usually when I shoot, I look at the exposure meter scale in the viewfinder and adjust the shutter speed (or aperture). Sometimes even after doing this, I take a picture first and check it in the LCD screen to see whether it is properly exposed or not (the way I want). If it is under/over exposed, I will adjust the the shutter speed or aperture so I get the result I want. This is the technique I have been following.
Now I am going to try some long exposure photography. For example I want to shoot the skyline at night where the buildings are well lit but still get a night feeling. How do I determine what shutter speed I should use? Should I do the same thing? Take a 30 seconds picture, check the picture, and if I don't like, change the shutter speed and keep trying this?
I shoot with a 50 mm f/1.4 on a full frame and I am looking to take pictures like this one on Flickr by Matt Pasant.