Do not trust promotions and giveaways
Do not trust fantastic "discounts", "promotions" and "giveaways". When taking part in giveaways, especially organized by well-known companies, check whether the giveaway is mentioned in official sources. Large-scale promotions are always mentioned on a company's official website and social media pages.
Pay extra attention to requests to pay "commission". In legitimate giveaways, winners are usually not asked to pay for shipping, commission, currency conversion, etc.