Once you have package control installed, it is super easy to install any plugin, theme, color scheme, syntax that you want!
You can search for packages on this website: packagecontrol.io, or simply search for some key words when you decide you need to install a package (see below).
From ST, bring up the command palette, and type
install package until
package control: install package is hightlighted, and press enter.
Wait a bit, and a list with all the package available will come up. Type the name of the one you want to install, and it
Note: It is safe to restart sublime text after you've install a package. But it become less and less useful (sublime text gets better, so you almost don't need to now). So, just restart it if something is weird, not just because I said it.