There is several methods you can use. The simplest one would be buying high quality PBNs, which can be expensive. Depending on niche, but to some level forum and comment links still work, but you need to works smart here. Outreach is good method if you have time. It takes a lot of time, but results can be pretty awesome. You can try to publish articles on guestpost sites and news sites that accept freelance writers. There is many ways you can get links.
But if you're not familiar with building links, you can always approch different method. Your main goal should be getting more traffic, which you can get by improving ranking with more links or create more easy to rank content. I would suggest you dig out as much long tail keywords with shitty competition and you write long (1000+words) quality content articles optimized for that keywords. You can try to write articles with keywords that have bellow 260 searches a month and you can get bunch of easy traffic, but you will need to write a lot of articles (50+). Just check that 1st page results don't have a lot of affiliate sites or big authority site. 2-3 big or affiliate sites are ok. If there is more just skip. You'll be able to rank for KWs like this withouth building a lot of links since you'll be able to rank site on site's authorty alone.
