Configure Raspberry pi for my application to start on boot

I have created an application through Python that has library dependencies on Qt4, pyqt4, pyqtgraph etc. This application is based on Raspberry Pi, I have developed and finished it on the platform. I want to configure Raspberry Pi to only run that one single application. When I power the Raspberry Pi, it should not go to desktop but run the application (eventually only use necessary packages,library etc). I have been looking around on different forums on how people do it, but it's not what I'm exactly looking for. There are also different solutions but it's just a bit confusing, that's why I'm here asking for advice/tips on how to implement that. So far I've tried sudo /etc/profile and at the end of that file I call python3 /home/pi/test.py where I execute my application. But I get X cannot connect Server error and Virtual Keyboard Florence is not really registering the button pressed.