Obviously depending on the time of the year you will need to bring adequate clothing. From December to March expect to bring winter clothing including hats, gloves and winter shoes. From April until October you should definitely bring T-shirts, shorts and comfortable summer shoes.
Whatever time of the year don’t forget to bring your sun protection – the weather in Austria is often much better than people imagine! Further details of what to bring will be finalised once you know which activities you or your group will be doing.