Of course the #1 white hat link building technique is link bait - having such amazing content, features or tools that other sites want to link back to it. But these sites must find you first, which usually involves some other source of links.
So what are the most widely accepted in Google's eyes, of attaining white hat links - or links that will in no way jeopardize your site's rankings.
These are the links that likely cost time and money, but are still worth it.
1. Guest blogging - spending time and effort on writing compelling enough content, that a blogger will want to use it on their site, and in return place a link back to you.
2. Article submission - creating great articles about particular subjects that news sites, and similar, will want to publish - that may or may not also reference back to your site.
3. Link requesting - pro-actively finding sites that are relevant to yours, or who's visitors may benefit from seeing yours, and persuading the site own to link to your site, or a particular page on your site.
Anything else - I am not talking about the latest manipulating tactics, but evergreen tactics that will offer mutual benefit.