That room should not be too dark or illuminated, or too warm or cold (the concept of too much is the origin of all the distresses).Simplicity and cleanliness should be protected. An image of Buddha, a Bodisatva or a Saint should be put on an altar located in the centre. This way, no demon or evil spirit could disturb you.
You can light some incense, a candle or offer flowers. Buddhas and Bodisatvas, that preserve the authentic teaching, will project their light over that place and protect it. If you do it this way, that place, no matter how small it is, will become into a true dojo, into a place of high spiritual dimension.
Text taken from the book “¿Qué es el Zen? Introducción práctica a la meditación Zen”, by Dokushô Villalba. Ediciones Miraguano, ISBN: 978-84-7813-286-4. All rights reserved.