How to deal with Temperature Controlled Freight for the first time

Day one of temperature controlled freight. What are the top 3 things brokers need to know when starting to work with temperature controlled freight?

What are the main factors that control temperature in a shipment and how do you teach brokers to accommodate those temperature fluctuations?

What type of temperature controlled freight is the most challenging to move well? Grocery. Medical, flowers, frozen food.

What are the makings of a good temperature controlled freight customer?