Landscape photography is a little tricky since you need to have the perfect balance where the sky does not look too bright or the landscape too dull in the background while also enhancing the details of both the sky and the landscape at the same time.
Now you can tackle this issue by split neutral density filter. You can put this filter ahead of lens. The filter normally has two parts; clear one and the dark one. The dark part is normally placed over the sky to reduce its bright effect and the clear part of the filter is used for the landscape. This can resolve all your worries regarding a bright-sky-over-a-dark landscape effect.
You can find two types of split neutral density filters; graduate edge and hard edge. The former one is usually used for landscape photography for the reason that the graduated edge normally ensures smooth transition between the dark and soft parts. This proves effective when it comes to landscape photography as it gives a more subtle and natural effect.
On the other hand, the latter option is good if you are taking photos with a rather defined background particularly when the sun is on the horizon. Both hard edge and graduated split neutral density filters are available in a range of strengths. You can find both the varieties of split neutral density filters in a number of various strengths like N ND0.3 = 1 stop, ND0.6 = 2 stops, ND0.9 = 3 stops.
The strength of the filter basically depends upon the disparity between the light of sky and the landscape; the more the difference the higher the strength of filter will be required. Though you can find the split neutral density filters as glass screw-in filters however, usually the photographers choose Cokin P or some slot-in based filter system. It basically enables you to adjust the filter up or down and hence place the dark part where it is required.
With split neutral density filters, you can view the photo right after taking it and this is what gives it an edge over other ways of balancing exposure in photos. Moreover, it also reduces the effort you will be putting in with the software-based options.
However, the major drawback of the split neutral density filters is that it normally functions properly when the horizons are well-defined. However, in case when half of the photo appears dark and half bright, you can take some help of software to get it fixed.