Here is the process of how I plan a landscape photograph and which apps I use to work out locations and where the light will be at certain times.
I think it's important to plan but what will ultimately happen is you might find other shots in the location that you haven't organised which can be the best.
Location
You might be choosing a location that mean something to you or the location might be chosen by a client. Either way, each location will have areas which will look the best and make the location look its best. For this example we'll choose Bondi Beach in Sydney and we can do a bit of research beforehand to find out where and when the best places will be to photograph from.
Weather
You're always at the mercy of the weather so if you're hoping for a clear sky and it turns out to be overcast the only thing you can do is try again the next day, depending on time of the day this might mean a lot of early mornings to catch the sunrise.
Clear skies can be nice and a bit of cloud can look even better depending on the look you're after.
Storm rolling in from North Head in Manly
When to take the photos
Generally my favourite times to photograph are early in the morning or late in the evening in the 'golden hour' where the light is warmer and softer. Different times of the day have different light and different light give the different feel to the image. I want to photograph Bondi Beach in either sunrise or sunset so I'll use the app 'Sun Position' (I use it on Android but there is probably a similar alternative for iOS a similar alternative for iOS). This is one of my biggest recommendations for photography whether it's landscapes or portraits.
The app tells you what time the sun will rise and set and also gives you the angle where it will be at different times of the day. This is very useful because you can see that at this time of the year, the sun will rise from the sea over the ocean at 6:15am. There is a the headland at the North end of Bondi Beach but the sun will rise over the ocean and just miss it which will mean the light will hit the beach as soon as it rises. Remember the angle that the sun rises and sets changes throughout the year so it's best to check the app before you go out to shoot.
Sunrise at Vincentia Beach in Jervis Bay, NSW
I like to shoot towards the sun so the light hits the subject from behind and creates a nice edge light and gives some drama to the scene. Early morning and late afternoon are generally nicer times to photograph because you can use the sun as the edge light and have the ambient light from the sky as the main light.
Here's a quick diagram (artistic masterpiece) showing the sun and the ambient light in the early morning or late afternoon:
In the middle of the day the sun is higher in the sky and isn't diffused by the atmosphere as it is earlier and later in the day and it will be brighter and create harsher shadows. There'll also be less ambient light coming from the sky compared with the brightness of the sun. This isn't necessarily a bad thing to have harsh shadows and can give some impressive and dramatic images, especially in black and white.
The animation of the Android app 'Sun Position' shows the angle of the sun throughout each year.
Good luck, hope the above helps. At the end of the day the more photos you take, the better they will become and it's a lot of fun while you're doing it.
All the best,
Ben.