Depending on the activities, the equipment will not be the same. Generally, hat, sunglasses and sunscreen are essential.
Wearing a helmet is not always mandatory, but highly recommended, whatever the practiced sport. However, it is mandatory for activities like snowboarding or competition ski, and a back protector or other protection.
If you have any doubt regarding the choice of skis or snowboard, explain when renting for activity you do and the rental shop will help you get the correct equipment. You can also contact the ESF for any additional questions.
For outings on snowshoes or cross-country skiing, think about dressing triple layers: a breathable underlay, a fleece jacket and a windbreaker for example. You can get hot quickly during the activity and cool quickly once you stop.