getting back to SEO , need suggestions

I have been pretty good at SEO 5 years back. It was easier to rank and make money.
After that i moved to SEM and social media marketing and never got back to SEO.
Now want to try stuff again. I know it is harder to rank now, But still would like to try.
I want you guys to suggest me the working tools regarding

keyword research
Competitive analysis
Social Bookmarking (if it works)
ways to create PBNs ( if it still works)
And other necessary tools.

Some tips and suggestions would be great here

Read the forums use the seach button sorry no hand feeding on here .

Everythink you mention is on this forum in grate detail.

These tools are all mixed up these days. For example Ahrefs is doing some of what only Semrush used to do. And Semrush is doing some of what Ahrefs does.

I'd say Ahrefs for link analysis and Semrush for competitor analysis. For keyword valuation I think Adwords is still the standard.

Adwords for keyword research
Ahrefs for backlink analysis
The PBN sticky for PBN building