For me, location is hugely important in railway photography. Once a good location has been found, it is well worth re-visiting, especially at different times of the day and different times of the year.
These are taken at Townsendfold on the East Lancs Railway. This first one was taken in 2007 at the winter steam gala, and unfortunately the engines had just backed off and so were not putting much exhaust out (they are approaching a crossing so would need to slow down), but the light was very nice, and a double header is always worth seeing. In retrospect, taking it a few seconds earlier may have given a shot with more steam.
Next – same location, same time of year, slightly different focal length. I was fortunate that the other chaps who joined me had arranged with the driver to put out some exhaust, so the effect is superb. On another day it might not be as good, but the beauty here is that the train is visible for some time so a decent zoom will enable you to catch at least some exhaust somewhere along the stretch.
What is worth noting at a location is the position of the sun – this particular one is great for late afternoon shots as the sun is off to the right and doesn’t cause any flare, whereas in the morning, you’re looking straight into the sun. While that can be good in some locations to create a certain effect, here it would likely just ruin the shot.