That is the question that we'll be looking at today! In English the formal "you" ("thee," "thy," "thou" etc.) has fallen out of formal use. But as you probably know, the formal Sie and all of its grammatical forms are still used in German as polite forms of social address to people you don't know and to show respect for elders, figures of authority, and colleagues in the workplace.

I have known people who were friends in their personal lives, but who as colleagues at work addressed each other with the formal Sie. When uncertain whether to call somebody du (the verb is duzen) or Sie (with the verb siezen), it's usually best to start with Sie.

But if it's a less formal situation, and you note that others are using the informal du, there is a polite way to suggest using the informal du:

Hm, hm, danke, aber Sie dürfen mich gerne duzen, ich bin Eva.

Hm, hm, thanks, but you can gladly address me informally, I am Eva.

Caption 36, Das Lügenbüro: Die Bewerbung

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And you can simply ask, too:
 

Darf ich dich duzen? Oh, ungern.

May I address you informally? Oh, grudgingly.

Captions 32-33, 18 Miss-Kandidatinnen: beim Friseur

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Luckily, the person in the last caption was kidding, as they continue the conversation using the informal du. After spending some time among native Germans, it's actually much easier than you think to get a feel for when it's more appropriate to be less formal.

Fremde Menschen werden üblicherweise gesiezt. In der heutigen Zeit sind die Umgangsformen lockerer als früher.

Strangers are usually addressed formally with "Sie." Nowadays, manners are more relaxed than in the past.

Captions 29-30, Cettina erklärt: Sitten und Bräuche

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Being addressed for the first time as Sie can also be a bit alarming for younger adults:

Hat der mich grade gesiezt? Ja. -Oh, Janosch hat mich gesiezt, jetzt bin ich... Jetzt bin ich wirklich alt.

Did he just address me with "Sie"? Yes. -Oh, Janosch addressed me with "Sie," now I'm... Now I'm really old.

Captions 23-24, Free Birds Interview: mit Nora Tschirner & Rick Kavanian

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So while there's a very small chance that somebody might be offended if you accidentally address them informally, as a rule most Germans will be pleased to find a foreigner speaking German and make allowances for the fact that US Americans, at least, are generally less formal. In my experience, they'll even find it charming.

There's a likely apocryphal story that German Chancellor Helmut Kohl once told US President Ronald Reagan—or was it British Prime Minister Margaret Thatcher?— "You can say 'you' to me." The point of the joke being that Kohl's English was so poor that he directly (mis)translated Sie dürfen mich duzen.

Further Learning
Do a search for videos on Yabla German for duzen and watch the video results in their entirety to get a feel for when people feel comfortable shifting to a less formal means of communication.

The above is a common German phrase that appears a bit odd in English, in that it seems to have the prepositions "on" and "to" in it, but that's not the case. On its own, the verb zukommen means "to belong to" or "to be assigned to," but when you add the preposition auf, together with a direct object such as einen, mich, dich, sie, ihn, uns, etc., its meaning changes: 

BANNER PLACEHOLDER

Ich weiß ja noch nicht, was auf mich zukommen würde.

I don't know yet what would lie ahead of me.

Caption 83, 18 Miss-Kandidatinnen - beim Friseur

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Wir wussten, was auf uns zukommt.

We knew what to expect.

Caption 55, Fußball - U21-Nationalmannschaft

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...weil wir eben zu viele Einflüsse haben, die auf uns zukommen.

...because we just have too many influences that are reaching us.

Caption 29, Gamification - Wie Spielen den Alltag interessanter macht

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Wie wenn Störtebeker eine Hanse-Kogge auf sich zukommen sah.

Like when Störtebeker saw a Hanseatic ship approaching him.

Caption 89, Großstadtrevier - St. Pauli rettet HSV

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Die Koggen, die du heute Abend auf dich zukommen siehst...

The ships that you'll see coming toward you tonight...

Caption 92, Großstadtrevier - St. Pauli rettet HSV

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Damit war eigentlich nur gemeint, ob euch klar war, wie viel da auf euch zukommt.

I actually just meant whether it was clear in your mind how much there is in store for you.

Caption 20, Luxuslärm - Interview

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As you see above, depending upon the context, auf [einen] zukommen is variously translated as "to be expecting someone or something," "to be reaching someone or something," "to be approaching someone or something," "to be coming toward someone or something," and "to be in store for someone or something." 

BANNER PLACEHOLDER

Further Learning
Look at the examples above on Yabla German to get a better grasp of the contexts in which auf einen zukommen is used so that you can better understand its meaning and learn how to integrate the phrase into your own vocabulary.