The ideas given here are general one, where every one can do it. This is not going to help websites to rank in Google. These links are highly recommended to increase trust flow of your website and link profile look natural. To rank you must target high authority websites on same niche. If these links are going to help ranking there would be heavy competition because even a beginner would not have trouble to get links from yahoo answers and Reddit. Links from Yahoo articles is somewhat hard which need high quality and spam less link.