Who told you forum and social media is useless? I think your marketing materials is not attractive. Another factor is the niche, if you post bitcoin related ads to food, or celebrity no one will click your ads.
Which is the best way to promote products or refferal links? Social media and forums is total shit,no one interested in this.
For me, I think links becauase it is one click away to the people who use computer or cellphones. Many persons are using technology nowadays so link is so preferable to people. Link can also share to other social medias that can promote. Promoting using link is so useful and it is more faster than products. For me, link is the highly recommended thing in promoting someting.