This instructions were tested on Raspbian Jessie.
You should never directly connect an printer with RS232-interface (serial port) directly to a Raspberry PI or similar interface (e.g. those simple USB-sticks without encasing). Those interfaces are based on 5V- or 3,3V-logic (the latter in the case of Raspberry PI). Classical RS232 uses 12V-logic and would thus destroy your interface. Connect both systems with an appropriate level shifter.
First, install the packages available on Raspbian.
sudo apt-get install python3 python3-setuptools python3-pip libjpeg8-dev
You can install by using pip3.
sudo pip3 install --upgrade pip sudo pip3 install python-escpos