Question About Outbound Links ?

Recently, I been learning a lot about on-site SEO and I have applied a lot on my site.
I have installed Yoast SEO Plugin Recently after many recommendations, and After that I been modifying all my Posts to Get Green light on the Plugin.

Except that There is a Part where it says "No outbound links appear in this page, consider adding some as appropriate" ... I really Never Used outbound links on my site, So:

• Should I add Outbound links to My homepage and Posts ?
  
• They Must be Do-follow or No-Follow ?
  
• Should the Outbound Links be Directed to my top 10 Competitors of the same Keyword ? or for example to my Facebook Page ?

Thanks in Advance.

I dont worry about linking to other sites much. If you do link to a site don't link to your competitors.

You Can Use Wikipedia, Yahoo Or Any Authority Site!

But Not From Your Keyword !!

Also try recent news articles related to your topic.

I don't do a ton of outbound linking but when I do it's usually sites like wikipedia or huff post.

You need outbound links. Don't use your keyword like mentioned above. Link to white-hat websites that have similar but different content. Wikipedia is a good one. You can also use this to generate goodwill among others in your niche, but definitely not the top 10 competitors. Find a good piece of content and link to it. I use do-follow links.

This is kinda like the kindergarten rule "Plays nice with others" and it will help you begin interacting with your niche community. This helps set you up as an authority figure in the space.

Here's an recenr interesting case study abount outbound links and ranking effects http://www.rebootonline.com/blog/long-term-outgoing-link-experiment