So you decided to meet new people, yet you don't know what to start talking about. Here are a few ways to find common topics to get acquainted.

[edit] Steps

Greet the person, and smile in a friendly way.
Ask in a general, friendly tone, "How are you?", "How are things with you?" "Nice weather we're having!"
Go into general topics in common, such as
- current news, issues (avoiding hot button political debates, general stuff like elections)
- weather
- interests
- friendly topics such as food, music, weather, computers, movies, books, sports, fashion, etc. Just omit topics such as politics, relationship problems, other people's misfortunes, money, health ailments, philosophy, and religion.
Observe any visual clues to draw a topic out. For example, a certain wristband, watch, gadget.
Ask them what kind of genre (for example:Hip hop, R&B, pop, reggaeton, country, jazz, classical, and etc.) of music that the person likes. Once they tell you, try to think of a song from that genre that you know, and could use to get the conversation started. Sometimes simple things like these are really good conversation starters especially if the person happens to like the same kind of music that you do. You can discuss different bands, or singers. Discuss maybe what concerts you have been to, or would like to go see. Ask them what kind of concert they would go to if they had the chance to.
Ask them what their favorite food is. For example you might want to ask them if they like Mexican food. Once they reply to you, you respond with your kind of favorite food, and then you proceed to ask them which restaurant they like the most.

[edit] Tips

A simple way that often helps strike up a conversation is to compliment the person, and then ask a question, eg. "I love your top, where did you get it?"

Asking about the weather in Britain can result in a lengthy conversation - British people have the ability to talk about the weather for far longer than is necessary, this can both help and hinder you, so be careful.

If you are talking to other teenagers (or other adults), they generally like to talk about music, sports, TV, celebrities, video games, cool websites, etc.

Younger children like to talk about their toys, video games, music, TV shows, food, etc.

General topics to avoid: Religion, Politics (unless it is something general, like the elections), Sex, Philosophy, World Problems, Death and Divorce, and the other hardcore topics.
If you choose to introduce yourself, use only your first name. While you may have the best intentions, the stranger you've just met may not.
Be safe. If you are young, do not talk to suspicious looking people.