I have been selling stock photos for a while. But sales is not very good. I would like to seek some pointers to improve sales.
Hi and welcome!
I'll comment on your travel stuff since still life isn't my thing.
You were unlucky and you visited Cinque Terre on a cloudy dull day and unfortunately the colours don't show (although you got a hint of sunshine in one of our pics). Clients rarely download cloudy images of colourful places for obvious reasons.
As for your other travel pics, they seem to be the same angles as 1000s of others and look overprocessed (HK and Manhattan).
The milky way shots look awesome.
Overall, a good start. Lastly, I would suggest to try to use more models (model-released) within your shots to increase their value.