Link building is an important part of any SEO campaign, as links provide the most valuable ranking information for search engines to use. Here are the main mistakes people make when building links.
#1: Asking someone to put in a link when they specify that they do not provide this service! Guest posting is popular, but lots of sites say they do not accept guest post contact and do not offer text links etc.
#2: Links onto a hacked site! Hacking isn’t always immediately obvious, but it can be found by running a site:search query.
#3: Non indexed sites offering links! Using Google for your discover, then this won’t matter to you, but it is important that the page you are getting a link on is actually indexed. There are some sites which at first glance seem good, with good metrics but are actually non indexed.