Set up Automated Shipping on Shopify Store

We have our shopify website almost complete and are looking for someone to set up the automated shipping based on customer zip code or postal code, we are only shipping to USA and Canada. We have installed Zapiet and Postcode shipping apps in our store and are looking to add the Boxify app to allow for better consolidated shipping. We need someone that will set this up accurately so we do not get overcharged for shipping costs in the end due to error of set up.