If you want to develop application for smartphones, you will need some hardware and software to start working.
Here is what I use to build native application for iOS, Android and Windows Phone.
> iMac 27″ : required to compile iOS application, enough powerful to have a VM with Windows working well
> iPod Touch 5 : try my apps on a real device at lower cost
> Galaxy Note I with a custom ROM which allows me to change the phone’s dpi and with Android 2.3 so I can still check that my apps works on old smartphone
> Nokia Lumia 930 : for Windows Phone application (and as my current phone)
Those devices allow me to test my app by myself on real devices. I feel like I develop faster by testing on a real device than the emulator because it builds faster.
> Inkscape : I love SVG as much as XAML. That’s the main reason why I create most of my assets with it.
> Mamp : Apache, Php, MySQL.
> Visual Studio Code : a light editor with Visual Studio shortcuts. I tryed it because Notepad++ isn’t available on OS X.
> Xamarin Studio : the main EDI I use.
> AppceleratorStudio for Titanium development.
> Vivaldi as my main web browser & mainly Safari to inspect my HTML elements.
> MySQL WorkBench : to modelize and manage my database.
> OneDrive : to keep some files available from everywhere.
> FileZilla : to upload my files.
> Virtual Box : to launch a Windows 10 instance so I can work on iOS and Windows Phone app with Visual Studio at the same time.
> Balsamiq Mockup
> Notepad ++