Open up your settings in Atom, select 'install' from the menu on the left and search for these helpful plugins:
Number one is missing because I will reveal it to your later in the cohort... it's super secret fun times.
Pretty obvious by the name, allows you to open files in your browser from Atom by right clicking!
Much like the equally helpful Chrome extension, this makes choosing colors for your CSS file much easier.
Right click or press CMD-SHIFT-C/CTRL-ALT-C to open it.
Automates closing of HTML tags, saves tons of time.
A preview map of your code, much like sublime. Pretty cool.
This one is more fun than useful, different file extensions are assigned icons and colors!
Lastly... this one is just for fun. Code like a gamer!