If the person is a stranger (someone you don't know) be careful what you talk about. Do not talk about personal things, e.g. your age, your relationships (boyfriends/girlfriends), politics, religion, or your opinions about other cultures. Talk about simple things like language problems, why you want to learn another language, where you live, the kind of work you do, the courses you are studying, the countries or places you have visited, the weather where you live, and everybody's favourite topic "food". Be careful, some people just want to play and some people want to meet someone to have a relationship (like boyfriend or girlfriend).

Topic's start depends on a style of conversation you have. If you want a non-official conversation, you can start speaking by whatever you want to discuss. If conversation is going to be a serious, you should use the kind (polite) phrases. For example: Good morning. I'd like to take a moment to introduce myself. e.t.c. Use more common phrases like a "first of all; as matter of fact; as well as I know etc) And the most important thing that's to have a "plan" of your conversational. You should understand and fallow to an information-plan you have to tell.

i`m learning...

I think it's really a question. I have seen my teacher open the dialogue like this: oh, i like your T shirt. it's natural and then we can talk about others.