I have been getting most of my backlinks from social media websites like Pinterest, Twitter, etc... How do you get backlinks to add SEO value?

Google Calculates Twitter Links as a Link, Pinterest too gives a NF link. but i would suggest you to use G+ which will helps you Rank Soon.

by active on G+ may helps a lot to you to Improve your SERP

If your site is validly offering a service, check the local govt. town county state etc, for "local business" links. A link from an authorative site is invaluable

You have been getting nofollow links from most of the social media channels. Getting nofollow links are kind of useless. However, your website can get so much referral traffic from social media channels. We do blog promotion, forum posting, PR promotion to get backlinks and SEO value.

You can do guest blogging and also you can build your own PBN network to build backlinks which will adds value to the SEO.

you can also submit your website in business listing websites where you need to provide complete information about your company profile,services,contact address( NAP format), products if any

Use Facebook, Google+ and try some guest blogging and article submission.You should do well.

It is not bad to get backlinks to your website from social media sites, but it will be best to get backlinks from the website of your niche because the value of link got from your niche has been high comparing to the backlink got from the socialmedia websites.

do best quality work.
do-follow rule apply in site
contents are unique & effective
tag , title , description are also effective.
more work on off-page.

we also follow for our web : discover-web-design-Adelaide

No follow link buildings are helps to get more traffic but if you want improve your website rank you will build do follow links with help of Off Page SEO activities.