Aside from here, where else?
Social media is a good place to learn about new altcoins due to the social media bounties so people are always posting about the new coins. From there I just follow the coin, go to their website, check it out to see what they are working on and if they are good then I could start to invest in it. Facebook are full with people posting about new coins
Why do you need social media to learn about new altcoins whereas most of the altcoins are being announced in this forum. I guess to filter out the good altcoins, you probably need social media. But, if you are able to analyze the project and their future then definitely you need not to look for anywhere to find out good altcoins.