I would also recommend working with other people that are already viral, make key alliances with similar programs. Make a video together, create a product or an initiative in cooperation. Also, use hashtags! People are constantly looking to do good, we just have to make them find it. Use pictures, good design, find people that are famous on social media (instagram, twitter) and have them team up with you, you’d be surprised how many of these people are interested in working on social campaigns.