Though the process of installing Sublime Text 3 on Fedora 21 is not difficult at all, the articles available online doesn't have the correct steps most of the time. Since I had to waste a decent amount of time to find the right script and install Sublime 3 on my machine, I thought I would document the steps, saving someone else's time.
The steps for installing Sublime Text 3 on Fedora 21 are:
Step 1: For Linux x64:
wget -O install-sublime.sh https://gist.github.com/xtranophilist/5932634/raw/sublime-text-3-x64.sh && sudo sh install-sublime.sh; rm -rf install-sublime.sh
 For Linux x32:
wget -O install-sublime.sh https://gist.github.com/xtranophilist/5932634/raw/sublime-text-3-x32.sh && sudo sh install-sublime.sh; rm -rf install-sublime.sh
The content of these scripts can be found here : https://gist.github.com/xtranophilist/5932634
su -c "sh install-sublime-text.sh"