Instagram, Facebook etc. G How to advertise and increase followers?
Learn SEO & digital marketing
Do you know a good tutorial or class for SEO? Or hiring someone would be better?
Depends if you want to spend money. But I would suggest do this yourself initially https://www.youtube.com/playlist?list=PLifnQOsGyOSRMYndHku6pNlLYckbBuOGU
Betalist, SEO, paid content and/or LinkedIn/FB/Instagram campaigns (depending on market) by influencers. If you have the budget, go to PR firm and get some articles placed in tech press too.
Spam
Hah hah. Are you serious?
Email them until they put you in the spam folder or accept your services. Then urinate over them to establish dominance.