The best place to practice Qigong is outside.
Outside in a city park, or in nature, or in a rain forest. Qigong is best out of the heat of strong sun, and under the shade of a favourite tree. It helps to have water nearby. Choose a place you feel comfortable with.
If you train on the beach, then train in the early morning or during the evening.
For more information about the hows and whys, have a look at what Dr Yang says in 'The 24 rules of Qigong practice' or this article about Adopting Qigong by Hilda Wei Williams.
Remember that Qigong is a dynamic experience. There are 'rules' laid down by practitioners who came before us, but they are not set in stone.