Waterproof shoes and windproof clothing are essential. Wear layers to stay warm. Check the weather forecast before you set off, and bring enough food and water to last the trip. If you are not familiar with the hike, contact locals and bring a map. Always let someone know where you are going and bring one or two phone numbers to call in case of emergency.
Recommended Outdoor Clothing, Winter
Your inner layer of clothing should consist of textiles that absorb sweat and keep the skin dry. Avoid cotton against your skin. The next layer should insulate, like wool, fleece, or down, for instance. Your outer layer of clothing protects you against wind and rain. Wear a windproof and water-resistant jacket and trousers. Avoid cotton trousers or jeans underneath. On your head: Fleece or woollen hats retain your body heat. On your hands: Mittens are best because your fingers "share a room". Fleece or wool underneath, windproof mittens on top. On your feet: Wool or fleece worn directly against the skin retain warmth and absorb moisture. Waterproof mountain boots are a good investment.
Recommended Outdoor Clothing, Summer
The weather in Vesterålen can be extremely changeable. Even though good, warm weather is forecast, wet and brisk intervals may occur. You should therefore bring along a windproof and water-resistant jacket and trousers. A thin hat or headband is a good idea for boat trips or mountain walks in case the weather gets a bit brisk. Bring thin gloves, too. They are good to have in case of chilly weather. Sturdy hiking boots also help to ensure a comfortable trip.
Remember to check the weather forecast!