How can I initiate conversation with a stranger?
First impression is one thing which leaves an everlasting impact on people we meet. So, meeting and greeting everyone with a smile is the key to leave that pleasant effect. 

Next, talking about general topics based on where you are meeting interests the person to talk to you. Make sure to ask open ended questions so that the person have the opportunity to speak a bit more.

Listening is the key to have a good conversation. During initial general conversation, try to find common interests to take the conversation forward. Make sure to show interest in the person you are speaking to.

Body postures also is an important part of being a pro at conversation striker. Positive gestures and body postures makes one take interest in what you are speaking and also, make anyone feel you are interested in listening and making friends.

Finally, practice makes a man perfect. If you are a beginner, try setting goal for yourself. For example, determine yourself to talk to at least three strangers in a week and try increasing the goal and one day you would be able to initiate a conversation effortlessly.