Beginer off-page SEO

Hi guys ! I am a total beginer.I have experience in web design but not SEO.I have created 2 money sites in good niches that rank well ( 2nd page ), just with on-page SEO.

What would be your advice on begginng to create backlinks to those money sites?

I am also a bit tight on the buget, and i can't start my personal PBN for the moment.Is there any chance i can do some off-page without money?

Thank you guys !

You can use some off activity for free likes
# Profile Creation
# Business Listing
# Business PPT Sharing

You can use
Profile links
Real Estate listings with your site link
Business Listings
Guest Postings
Guest Bloggings, etc.

Build your own tier 1 links for limited budget. And as for tier 2 use GSA SER service here on bhw (it's cheap), then submit them to indexing service.

Create Web2.0's on your own and blast them with Cheap links (100 pbn posts for 10$) or GSA Blast for 5$ or something like that.

This will be cheap and will help you as well!