In which cases would you approach the Up selling technique?

1- If I can make the customer see the value of money and the benefit that he getting , Then I can make him spend more on the products that complement the primary product.

2- the easy way is if the customer tell you that you are on a budget

I am sure you would have heard of a great quote made by Nepolean B - Men are moved by two levers only - Fear and Self Interest. I would like to tweak it a bittle to suit this question - People are moved by two levers only Fear and Love. 

Fear is a driving force for a quick sell example while booking a air ticked 60 % of people oprt for insurance which is just a penny amount in fear of missing the flight, delay in flight, loss of luggage. People are concerned of their safety and will go for safest product compared to low cost one when it comes to their health, safety and security. 

Love is another drivgin force. When a customer is loyal you can pitch for upselling it showing the benefits in near future. Customer look for the best when it comes to their Family - wife, kids and parents. Gifts, antiques, precious metals. are the ones when in upselling model fits the best. 

There is not stepping stone or a full proof model which guarantees a sale. Its is all your cautiousness, wisdom to go for a pitch depending on the customer mindsets and his bidy language.