I think all of these tips are stating the obvious, but I have made all these mistakes whilst starting out. (and still do occasionally!! )
Prepare your equipment before you travel
This is the most important thing I do when I am heading out shooting. I make sure my lenses are clean, batteries charged, memory cards wiped and that I have everything I need in my bag. There is nothing worse than rooting through your bag during a cold winter shoot.
Plan your location and journey
Choosing a location that interests you is very important. Plan your route and the time of day you wish to shoot. Check the weather. There are useful apps like Photopills that is a great tool for understanding sunrise/sunset points. This can help maximise your time at the location which will give you more time to find the right composition. There are lots of books and groups out there to give inspiration for places to visit.
Landscape photography requires a lot of patience. Waiting for the right light to appear that can make or break a scene or walking a bit further up that very high hill to get the right vantage point. I’ve also learned to be patient in the sense that I am prepared to visit a scene a number of times to capture it in the best possible light and conditions. I have gone away from lots of journeys feeling disappointed and having taken no worthwhile shots. I have always made the effort to go back.
Carry a tripod
This is very important for a number of reasons. For me it helps me slow the process down and ensures I take the time to compose my shot. Another good reason is that I can allow for a longer shutter speed which is useful in numerous scenarios such as waterfalls or when the light isn’t quite at its best. I don’t have the steadiest of hands, so I feel a tripod helps eliminate any shake and keeps my shots pin sharp. Remember to turn IS off on your lens if you are using a tripod.
Invest in some filters
I think this is one of the best things I have done and I really noticed a difference in my photographs. I regularly use Hoya ND and Polarisers and I have invested in some KASE graduated filters. These really help balance the exposure and minimise the work when editing.
I hope some of these tips help. The best way to learn is to simply go out and shoot. Experiment with your settings and get to know your camera and equipment. I would recommend shooting in RAW. This gives maximises the information the camera captures and allows for a much easier journey through the editing process.