Staying in Artemida for 9 nights.
What is the best place for beach, any less crowded, secluded, calm ones?
There exist some less crowded beaches in residential neighborhoods. However they are usually with rocks and are not shallow.There is a more secluded one not too far from the Xristina Taverna in Vravrona which is a short walk from bus stop 5.This is the Davis Beach area. There are many beach areas with soft white sand along the main road through the town. They are very crowded in the summer. Most restaurants and cafes provide sunbeds and umbrellas for the price of a coffee. There is also the Agios Nikolaus beach area which is also very busy and Vravrona has many places which also provide sunbeds.
I would suggest Davis beach. The water is clean and the sand is nice. However it is not the calmest one, but is not crowded too. The days you would want to avoid are Sundays and Saturdays because the beach is full with people.