I would say go with resource page backlinks. Find websites and blogs that have resource pages or link to other websites. Some webmasters use page titles such as: Friends & Partners, Resource Page, Links etc.
Most webmasters use this page to link back to their friends, favorite websites and sites that link to them. So you can take advantage of this, simply go to Google and use one of these search strings:
"keyword" + inurl:links
"keyword" + "helpful resources"
site:.gov + "resources"
site:.edu + "keyword" links
Now, after finding those sites you can simply contact the website owner and ask for a link exchange. You'll find that some websites do allow link exchange and those will be easy to get. Make sure that you have good quality content before you even think about doing this.
Here's another trick you can use: As you're browsing these websites check if there's any broken links. If you find one then simply ask the website owner to replace it with your link, most of the time they'll say yes and Thank you.
Another ninja trick, that I've never shared with anyone and hasn't seen a lot of people talk about. Take the broken link and put it on any backlink checker tool. Find all the websites that link to the broken link, contact the webmaster and ask them to replace the link with yours.
There's a lot of ways you can use like interviewing a webmaster then ask them to link to the interview. Or using list posts like "Top 100 Blog Posts That Will..." After making the list post you contact the featured webmasters and let them know you linked to them and they might link back.
Once you start getting traffic to that list post, eventually people will visit those sites and webmasters will see (in their traffic stats) that you're bringing them traffic and most won't mind returning the favor.
I can go on all day but hope that helps