That is indeed a very interesting question! As Ian has suggested for sunrises, fronts advancing from the west are a good indicator, and for sunsets, fronts clearing to the east. However, any situation where the sky at or just below the observer's horizon is clear will work, and there are non-frontal situations which can give that. Some are very difficult to forecast. Think about those random banks of stratocumulus in winter that give the forecasters such a nightmare with regard to predicting frost.
I find the most interesting sunsets are where there is cloud overhead at multiple levels and the setting sun illuminates each level in turn. This can result in a spectacular sequence of shifting patterns, shadows and different colours over quite a long period, whereas a single level cloud bank can give spectacular results, but sometimes with only a single colour, and often very briefly.
Regarding location, you are better off near the coast, as the high concentration of salt particles suspended in the air over the oceans increase the amount of scattering out of sunlight the shorter wavelengths(violet and blue), giving sunsets a redder hue.
However, as well as being alert to the conditions, luck is a large part of it I'm afraid.
Rob
In the flatlands of South Cambridgeshire 15m ASL.