 Amenities inevitably come hand in hand with crowds, so on the main beaches be prepared to do battle with lots of other sun-seekers, all equally happy that restaurants, toilets, showers, and changing rooms are there.
If you are willing to go without amenities such as restaurants, toilets, showers, and changing rooms, or simply go with less of them, you will find the smaller beaches to be less crowded, though also less convenient.