Nowadays, in some countries, telemarketing is considered as a harmful phenomenon, this is due to the fact that phone solicitation is associated with fraudulent sales and forcing sales. What is the best techniques to catch the attention of a potential customer?

its so simple ..make sure you have a quality products and services and alongside a skillful sales agent who can easily convince customers in a positive manner 

Just greet nicely in start and smile to the customer before anything else. Then talk them like what brings them in the store. If they have the answer so thats the time will start it to let them know the things that they're lookig for. And let them know the uses and advantages about the things for the needs in such things there looking for. 

Fact finding about the client and ensuring you concentrate on the need and provide a matching product/service/solution within the estimated budget based on the market