Hi. Not sure if this is the appropriate place to post this, sorry if it's not. But I've been trying to add grain to my landscape shots but can't get it to look authentic or pleasing. I think this shot has got what I'm looking for, I'm just not sure if it's acheived in-camera or in Lightroom using a process/preset/technique I don't know yet:
A "pleasing" grain effect is very subjective and open to interpretation. Grain can be used to simulate photographic film looks, or to add an artistic effect, or to make a photo look aged, or to disguise noise, or a number of other purposes. What are you trying to achieve with adding grain? It will help us if we better understand your vision and goal.
Next, please let us know some details about your image - pixel dimensions, file type, etc. Please also tell us what settings you are using for adding grain, as the settings will vary depending on file size and resolution.
Also, grain is hard to see in a reduced size image as you posted; it would be good to post a small patch of your image at 100% zoom level to help us see what you're seeing.