Offpage SEO refers to techniques that can be used to improve the position of a website in the search engine results page (SERPs). OffPage SEO has to do with promotion methods with the aim to get higher rankings in the SERPs. Unlike On-page SEO, Off-page SEO refers to activities which are performed outside the boundaries of the website. The most important are: Link Building, Social Media Marketing and Social bookmarking.
Many think the more links, the better but it doesn't actually work that way. Too many low quality and/or spammy links and your website will lose Google credibility and therefore visibility.
Since a few years already, you as website owner are responsible for the backlinks pointing to your site, so you need to constantly monitor, identify bad links and clean up your backlink profile. First step using the disavow tool then to try pro-actively to remove them.
Off page SEO gives search engines an indication on how other websites and users perceive the particular website. A website that is high quality and useful is more likely to have references (links) from other websites; more mentions on social media and it is more likely to be bookmarked and shared.
Link building is the most popular and effective off-Page SEO method. By building external links to your website, your trying to gather votes of confidence from other relevant websites. Old methods which now do not work: blog directories, forum signatures, comment links, link exchange, Reality is quality of links than the number. To get quality links the best is to understand what content you can produce that will add value to potential customers and to influencers and then bring it to them:
Getting a backlink that appears on every page of a site is rarely a good idea especially if it not set as nofollow. First the position of the link on the page is a key factor so if your link is in the footer its positioning is all but optimal. Second, your numerous backlinks will in fact count as only one and its value will be minimal if negative. Other type of links to avoid: links from unrelated websites, from sites of different languages and/or countries and from websites flagged as spammy
Once you have identified those toxic links, the best is first to use Disavow Tool to inform Google you are aware of them and want to bring them to Google's attention. Please note that you need to be connected to the website's Search Console account in order to log into the tool. Google then advises you to actively get in touch with the respective webmasters and ask them to remove them.
Social Media is part of offpage SEO and a form of backlinking which could bring you traffic and recognition. Although most of the links from social media are nofollow they still have value. Social Media mentions are gaining ground as ranking factors and proper configuration of social media profiles can also boost SEO.
Social bookmarking is not as popular as it used to be in the past but it is still a good way to get traffic to your website. Depending on your niche you can find web sites like reddit.com, stumbleupon.com, scoop.it and delicious.com (to name a few) to promote your content.