customising existing E commerce site theme

Description

this is the theme that I have purchased, which I really like. I want to customise this theme to make it unique for me and then use it for other sites in my portfolio
The theme is this:
https://themeforest.net/item/elessi-woocommerce-ajax-wordpress-theme/20968615
id like to do customsation in stages, to discuss ideas, and develop it over time and turn it in to a great ecommerce store