Packages

Package Control is already built-in by default. (It used to be a separate package to install) So no need to install it manually anymore 👍

Install Packages

Hit Command + Shift + P > Package Control: Install Package and type in the names of these packages:

Alignment: Easy alignment of multiple selections and multi-line selections

All Autocomplete: Extend Sublime Text 2 auto-completion to find matches in all open files of the current window

AutoFileName: Plugin that auto-completes filenames

BracketHighlighter: Bracket and tag highlighter

FileDiffs: Shows diffs between the current file, or selection(s) in the current file, and clipboard, another file, or unsaved changes

Git: Plugin for some Git integration

SideBarEnhancements: Enhancements to sidebar. Files and folders.

SublimeCodeIntel: Full-featured code intelligence and smart auto-complete engine

SublimeLinter: Interactive code linting framework for Sublime Text 3

TrailingSpaces: Highlight trailing spaces and delete them in a flash

Install Themes

You can simple go to package control and search for themes. I would recommend using the Material theme or Brogrammer Theme.