I've said this a few times already, but timing is everything at sunset. Here's an example of a photo I took last week. I found my spot, setup the shot and took a photo every 30 seconds or so until I was done. From memory I must have taken about 20 shots of this one scene, probably too many but it's not like I was doing anything else at the time.
This photo was taken at 6.46pm:
It's ok but not great. There's a bit of colour in the sky at this stage. But it's always worth sticking around until it's too dark for a good photo just to see what happens.
And six minutes later at 6.52pm this is what happened:
Both images have had roughly the same amound of post processing done to them, I adjusted the shadows in the rocks on the second one so they weren't so dark, but they've essentially had the same treatment done to them.
Moral of this story: be patient and just wait for that right moment when the sun works its magic. Sometimes it'll be a fizzer, but just maybe you'll get something awesome.