Another tool in improving the look of your images is to carefully watch your backgrounds. Pay particular attention to man made objects such as telephone poles, street lights, signs, cars, etc. These can be very distracting to the image you shoot, and considerably take away from the composition and strength of the shot.
Many times, these distractions are easy to fix, if you are paying attention. Moving 3-5 feet may allow an object to be hidden, or no longer be in the frame. Or perhaps, crouching will allow the top of a pole or other tall item to be hidden by the train. If not, perhaps a lower angle from a ditch, gully, or other spot below the right of way. This technique will require shoot upwards towards the train as opposed to the more typical track side shot, but this type of angle can hide many distractions. For example, behind the shot below is a track side signal, easily hidden by the low angle. Also, a major interstate highway is also on the opposite side of the tracks. Had a more normal, at grade shot been made, or a shot with slight elevation above the tracks, not only would the signal likely be showing from behind the train, but an interstate highway with numerous vehicles would have easily been seen, very much distracting from the scene. However, by going low, all distractions have been removed, with a clean sky behind the train, with attention to the subject matter, the train, considerably improving the shot.
At other times, it may not be possible to remove the distraction by simply moving, or lowering your position. Another technique that can work would be utilizing a longer focal length combined with a shallow depth of field. Although this may cause less of the train itself to be sharp, attention can be focused on the area of interest with the train, typically a head on shot (though a broadside could still work with this approach), rendering the background blurry and not competing for the attention of the viewer. Although the image below was not shot wide open at f2.8 or f4, the background still blurred with the utilization of the long lens (300mm), reducing some of the distraction behind the train. A more wide open aperture closer to f2.8 would have maximized this effect.
Yet another way to divert attention from a distracting background would be to utilize a wide angle lenses, particularly in the 16-20mm range. Wide angle lenses result in the closer subjects being largest, and objects further away becoming quite small (the opposite of telephotos that compress the shot bringing in the background)..
So, to improve the results of your imagery, keep a careful eye on the backgrounds. By carefully envisioning the shot, your images will significantly improve!