When to use formal and informal italian?

Question

for e.g informal: Pieccere de concerla

formal : Pieccere de conocerte

can you give me examples of situations where I should use each phrase.

Answer 1

express yourself in the best you can, the rest will follow

Answer 2

Use the formal phrasing when you are talking to anyone you have never met before. Informal may be construed as derogatory since you really don't know who they are. Conversing in stores, restaurants...same thing, use formal. If you return to a place and they recognize you, they may greet you informally and then you know you can too.

Answer 3

Smirkz got it! 10 points to him!

But remember, with child always informal.

Piacere di conoscerLA (to a man or a woman)

Piacere di conoscerVI  (to men, women or a group)

Piacere di conoscerTi  (to a children, boy or girl)

Pee-ah-céh-reh dee coh-nòh-shehr-LAH/VEE/TEE.

Answer 4

AND PLEASE

piacere di conoscerla

PIACERE DI CONOSCERTI

Answer 5

Sorry but i have to correct my italian friend who has written before me it's quiet correct but not at all.

Piacere di conoscerla .... when you're talking about someone older that you or in a formal situation /job, boyfriend's parents, important people, formal dinner....

Piacere di conoscerti.....with young people (not in job situations)(same age or younger than 30) and informal situations (party, gym, meeting of friends, disco)

I'm italian