If you are using anaconda with conda package and env manager you can start by creating the dedicated environment.
# Creating new conda env with python 3.6
conda create -n deeplearning python=3.6 anaconda
# Activating the freshly created env
conda activate deeplearningconda install theano
conda install tensorflow
conda install keras
# Update freshly installed modules
conda update --allpip install theano
pip install tensorflow
pip install keras