Bluetooth Low Energy (BLE) is now the standard communication protocol used by smart devices. If you are looking to get started with BLE, then you need two things:
1) Bluetooth Smart Devices: Those devices which gather information using sensors, later to be used for further analysis.
2) Bluetooth Smart Ready Devices: These are the devices which make use of the information gathered by Bluetooth smart devices to be displayed in human readable form.
Developer portal of official Bluetooth special interest group has provided lot of information regarding working of Bluetooth and how to use BLE in smart wearable or IoT devices to make it work seamlessly with smart phones, TVs, cars or any other smart ready device. If your immediate need is to make a smart phone application for BLE, then make use of the smart starter kit which has provided keeping beginners in mind.
Also, most of the embedded developers would want to make use of a development board or kit to get started, for that I would highly recommend making use of the list provided here, as these are the most reliable boards with proper software development tools.