Build Links with Quora
When it comes to building inbound links, Quora is the best technique. Posting high-quality answers to niche-related questions on Quora is the most working blogging strategy for getting links back to your site.
When you want to start providing answers on Quora, join the platform using your Gmail or Facebook account and you wouldn't have to encounter Google recaptcha challenges at all. A lot of folks have complained so much about the security challenges faced in the course of trying to connect to Quora.
Allow Quora to access your Gmail or Facebook account and you'll successfully get connected to Quora to start answering questions immediately.
Build Links with Forum Posting
Forum posting is another great strategy for building high-quality inbound links for search engine ranking purpose. Getting the first-page ranking is guaranteed with content and link building. These are the top two ranking signals in the search algorithm.
To make the most out of forum posting, join the high PageRank online forums such as the Warrior Forum - the #1 internet marketing forum in the industry.
Also make sure to add your website URL to the control panel of your forum dashboard as a signature so that it appears at the bottoms of all of your posts.
Build Links with Guest Posting
Through guest blogging, you can always link up to your ideal target audience and build high-quality links for your website.
If you offer guest posts to niche-related authority sites, you'll surely build high-quality links and get the deserved traffic.
The other methods you mention here are also good, though you don't mention YouTube ; ) I have just started my channel, well building it up and the engagment is brilliant, the traffic also, with over 88% coming from Google Searches