The form of linkbuilding considered to be most ‘white hat’ or ‘ethical’, that’s most highly endorsed by Google and the search engines which follow its example, is to simply let your product market itself through its inherent usefulness (‘utility value’) and the viral marketing that naturally occurs as a result of this.
If you have a useful product, irrespective of whether this is a physical item which is sold or simply the website itself, users will naturally build links to your site from various sources such as social media and blog posts to highlight its worth, and when the word gets out, authoritative sites will link to you too. This amounts to creating the perfect, ideal, ‘organic’ backlink profile.
A useful site not only attracts links, it also reduces bounce rates. In recent years, this is just as important (if not more important) for influencing rankings in the long term.
If you have a genuinely useful website then its visitors will be less likely to bounce back to search results in order to view alternative (competitor) sites, which would be tracked by Google. Meaning, you will be rewarded with higher rankings for the lower bounce rates, as search engines are heavily offput by these ‘back to search results’ bounces.
An important clarification to make here, is that your rankings will not be negatively affected by users who simply bounce off your site because they’ve found whatever information they seek or achieved what they wanted to achieve. So long as they don’t subsequently go back to search results and click through to the next result down, which would suggested that they didn’t get all they needed from your site, then your site has done it’s job. Plus, a bounce off your site that doesn’t go back to search engines is much harder if not impossible for search engines to detect (they would have to use data from users’ browsers, analytics tracking codes on your site, etc without your explicit permission, which would raise privacy concerns).
How can your useful site go viral if nobody knows about it in the first place?
People can only link to your site if they know about it in the first place. Thus, promoting your product by any means, such as networking with industry peers, so long as it’s with the aim of raising awareness of your product (rather than specifically for the purpose of negotiating links to your site) is encouraged by Google.
Google wants link equity to be granted on the merit of your site or product alone, at the publisher’s own discretion – not asked for or encouraged in any way, in order to be strictly white hat. The moment your outreach is for the goal of obtaining link equity (to artificial boost the perceived reputation of your site), rather than simply letting third-parties know about your site (as per white-hat, proactive linkbuilding efforts), then you are not building links in an ethical, white-hat manner endorsed by Google and you should be concerned that your rank-manipulation tactics may be detected and you may be penalised for engaging in such activity.