I haven't really perfected taking sunset shots yet... but first thing... clean the sensor
LOL!
What aperture were you using on these shots by the way? Your EXIF doesn't say since it was an M lens.
What it does say is in both shots you were using ISO 100. If I were you I might experiment with higher ISOs and various apertures. About 400 to 800 ISO could yield some impressive results, especially if you combined it with various apertures.
The good thing about digital is that it doesn't cost anything to experiment.
When I try to learn new things (like this) I always take a geek approach by logging down each attempt and what it resulted in. Say start wide open at ISO 100 and then do your ISO to 200 then to 400... then to 800.... Then stop down one stop and repeat.... then stop down again and repeat...
Personally I don't wait until I get a stellar sunset to go experiment... just go on pretty much any day... and you might take 50 shots but odds are about halfway in and you will start to get light bulb moments.