If you want to play a long-term game I suggest you start off slow just like any mom and pop would.
1. Social fortress - everyone does it and Google totally approves of that. Probably the only link type they accept when webmaster build them themselves.
2. Press release - let the world know you're out here. Repeat every time you upload a new piece of content.
3. IFTTT setup - automatic syndication of new content.
All of the above is to setup and grow authority, to become a "good guy" in Google's eyes. Don't expect any rank increase from these.
4. Analyze your competitors link profiles and replicate some of the links they have. That's what got them there partially.
5. Later on I suggest you get links from multiple places like:
blogging web 2.0s
video sharing sites
audio sharing site
presentation sharing site
wikis
Wikipedia
PDF sharing sites
etc.
6. Build a strong PBN for some serious rank boost.
Hope this helps a bit.