Listen to Grumpy SEO Guy episode 49 – the 4 ways to get backlinks
Listen to Grumpy SEO Guy episode 37 – the difference between good and bad backlinks
Listen to Grumpy SEO Guy episode 39 – the difference between good and bad backlinks part 2
You’ll know more than the majority of SEO “consultants” once you do.
Why are you obsessed with DA40-79? Are you checking the links besides that or are you just selecting them because they have decent DA? Are you looking at other factors besides DA? Are you looking at their backlinks, their anchortext, their IPs? Are you getting links on URLs with authority or on non-authoritative URLs of high authority domains? It’s not about “buying good DA backlinks.” The backlink game is complex and detailed and many vendors are scammers. Those episodes will help you.