Naturalism is a healthy way of using free time, it is an excellent pastime for children to recreate and at the same time learn to move in the open air. In the present very abbreviated work the basic principles to be followed by the beginner are contributed to make more fruitful their excursions to the nature; by fields, forests and lagoons. It deals with: the naturalist's wardrobe, the clothing to obtain, how to collect and create simple collections from nature, how to improve your garden, bird and mammal observation. Emphasis is also placed on the ethical principles that must be followed in order not to harm natural populations.