Establish accounts & contribute normally in all the Social Media (SM) platforms, including interest groups & collections. Do not post immediately but take a couple months to establish friendships and normalcy. Join a lot of topic specific Facebook Groups.
Do not get impatient and post too fast or it will be considered SPAM and likely will be removed, possibly blocking your account from further posting.
Make sure your Youtube profile image is the one that you want to represent you. I would recommend annotating it with your branding. This will be the image that will accompany the Youtube link you post.
Then when you're ready, start posting your Youtube links in all these SM sites and include useful, interesting content.