The ultimate goal is to have your own PBN as this is the absolute best way to rank sites nowadays. Imagine if you owned Forbes, Bloomberg and Entrepreneur. You would point backlinks from these 3 sites in your PBN to any money site you wanted and you'd rank instantly for whichever keyword you wanted.
Well, if you owned those 3 sites they would be your money sites and you'd be a billionaire anyway because these 3 are powerful enough in themselves, but you get the idea. So, start creating your own PBN ASAP if you can afford it!
Until then, to boost your site's rankings check the standings of your important URLs (not just the money pages but also the informational pages, although I would definitely start with the money pages) in GSC and check for 3 things:
1. pages that are not indexed yet (you want these indexed ASAP because - if your domain is authoritative enough - some of these pages could skyrocket to page 1-2 of google based off your domain's authority alone, I've seen this happen for long tail keywords on powerful domains when as soon as these pages got indexed they shot straight up to page 1)
If you find content pages that are not indexed yet, make a few internal links (with exact or partial anchor text) from pages that are already ranking, to these non-indexed pages and index them
2. pages that have been stuck around pages 2-3 of google for some time. You can boost the rankings of such pages with a few d0follow backlinks as long as they're quality links (PBNs, guest posts, niche edits).
3. (optional) create some engaging content (that offers a freebie or something valuable to visitors to make them click on your page and interact with it in general), and then run some social media promotion to that page. Google tracks stuff like this (well, they track everything) and if they see that your visitors like (and interact) with your site they'll reward you with better rankings.
I wouldn't waste my time with Fiverr. I mean, Fiverr is OK for certain things, but not for backlinks. Most of the backlinking services on Fiverr, SEO Clerks, and sites like these are scam or very low quality and might actually hurt your site (especially if it's new).
GSA I never used so I don't know what to say about it, and web 2.0s don't work as they used to, so I wouldn't waste my time with them, either. If you can get 10-20 branded web 2.0s that will not delete your content or account after some time (many web 2.0s do this) then get them if it's not too much hassle. But don't rely on them packing a punch in your rankings, that's all I'm saying
