zackproser

The Simple Twitter Follow Me button allows you to add a small or large Twitter follow button to the end of every post so you can grow your Twitter following with your blog readers and let your audience easily share your content on social networks.
Once installed and activated, go to Settings -> Reading and scroll down to the Simple Twitter Follow Button settings.
Here you can enter your Twitter username and choose whether the button should be small or large.

Simple Twitter Follow Me Button

This plugin is the easiest way to add an official Twitter follow button at the end of every post so your readers can follow you on Twitter.

demixpress

This plugin makes it even easier and better to display <a href="http://addthis.com" rel="nofollow ugc">AddThis</a> tools for your WordPress site, including share buttons, follow buttons and recommended contents.
To make this plugin to work:
<ol>
<li>You must have an AddThis account.</li>
<li>You CAN NOT use other AddThis plugins.</li>
</ol>
About Social Sharing Optimization
This plugin doesn’t do anything to optimize the social sharing results, if you need this, try a related plugin, such as:
<ul>
<li><a href="https://wordpress.org/plugins/wpsso/" rel="ugc">WordPress Social Sharing Optimization</a></li>
<li><a href="https://wordpress.org/plugins/wonderm00ns-simple-facebook-open-graph-tags/" rel="ugc">Facebook Open Graph, Google+ and Twitter Card Tags</a></li>
</ul>

(dp) AddThis

Makes it even easier and better to display AddThis tools (share buttons, follow buttons and recommended contents) on your WordPress site.

Simple Twitter Follow Me Button vs (dp) AddThis