CSGO offer/tasks sites are the safest way to earn CSGO skins for free. All you have to do is complete offers, such as watching short videos or completing a survey to earn CSGO skins. Using what's commonly referred to as an 'Offerwall', you can pick and choose activities and tasks you are interested in and most importantly, get paid for completing them. Some offers might be time or user limited, so don't delay in completing tasks or risk missing out on the reward offered. Reward payouts vary, so always shop around for the best value tasks to compete.
Key features to look out for: