How To Evangelise

Before the "how" it's useful to know the "why". Three reasons :

A) Jesus commands it
B) Everyone’s greatest need is eternal salvation
C) To see God glorified

Explained here.

So... How to evangelise? Here are some handy tips:

For example: 

Lead with a probing question. Ask a question that will lower the person's guard and get them thinking about larger existential issues, making them receptive to an exchange of ideas. A question like, "What do you think happens when you die?" or "Do you believe in an afterlife?" can be effective at transitioning the conversation into your territory.

A most effective evangelistic tool that you can use is a survey. You can ask four questions about an individual's life, and after you know the needs and beliefs, witness to each based on the point of view.