If you want to embed a Twitter Follow Button in your website you can use their Generator. It has limited configuration options.

To style it your way you just need to know that a follow me is triggered by calling the link

<a href="https://twitter.com/intent/follow?screen_name=leifhanack">Follow me</a>

where screen_name is the twitter account name. Either with or without leading @.

I like this solutions because it is plain and simple. No need to include their javascript. No limitation.

Photo by Todd Van Hoosear