Also, sometimes my shots come out too dark even with sufficient lighting.
If you see it's too dark, then open up some more. That's what digital cameras are for.
Meter off the sky to the right or left of the sun, not directly on the patch of sky that includes the sun. Or meter off your palm if there are foreground objects you want to see detail in. You may need a graduated ND filter to get foreground and sky detail. Or take two exposures, one for sky and one for foreground, and combine in post processing.
Don't forget to turn around and see what the sunset is lighting! Some of the best golden hour pictures aren't of the sunset at all!
Enjoy!
Become one with the P setting! You'll get some great sunset shots with that guaranteed.
Also, if you don't own one, buy a tripod and use it – a lot! Most people think they can hand hold at less than 1/60. They'd be wrong.
My wife and I both do a lot of outdoor photography and spend our summers shooting sunsets along the Huron shore – better than the Pacific and Arizona in my opinion. If we forget the tripods or don't want to lug them around, we always seek out ways to augment our support. Get your elbows on something solid, brace your torso against a tree or wall, etc. A steady platform is essential for good results.
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