How would you choose the best media to promote your advertisement?

the simple process is as follows.

1 - Understand your product and competition - let's say you are selling Laptops in UAE. What are your product attributes, offer and price difference based on competiton. 

2 - find the scope in the market you wish to sell - get statistics how many sold, how many required in20014, who needs them B2B / B2C, what is the potential market size for your product.

3 - segment your customer types - age, location, gender, likes, social elements, usage etc

4 - it would make it easy for you now to select the media. You know you customers so select the media they read or watch. 

We cannot refer to one medium a as the best form of media. Every medium has its own advantages and disadvantages and clearly depends on various factors like the objective of the campaign, the available budget and the target audience and geography. 

If its a mass communication campaign one would clearly opt for ATL through TV or Radio 

For targeted marketing - marketers prefer to use online media, SMS etc.

E-shots for cost effective campaigns

Hence, the choice of the media depends on the campaign objective and available budget.