There are many good ways of building links to improve search engine optimization and there are also bad ways of building links that might hurt your website ranking and get you a penalization that’s difficult to recover from.
Methods to avoid when you build links for SEO:
  1. Buying and selling  links.
  2. Using an automated link building system.
  3. Excessive link exchange.
  4. Building a network of sites with the purpose of interlinking them.
  5. Irrelevant links posted that are not related to the topic.
  6. Using low quality links.
  7. Using web-rings and link farms.
Using some of these methods might falsely boost your website rankings, but there is a great chance that your site will be penalized by Google in the future and it can take several months or more to recover. Google is always looking for quality web links and adding low quality website links is not the way to go.