At the airport: Check in counter

🇩🇪 [Guten Morgen] is the normal polite greeting in service situations in Germany, including airport counters. You can use it even if you speak no further German.

💬 [einchecken] is a separable verb, so it splits in a full sentence: [Ich checke ein] or with a modal-like verb [Ich möchte einchecken]. The [ein] stays attached in the infinitive form here.

💬 [möchte] is a softer, more polite way to say what you want than a plain [ich will]. You can reuse the pattern with another verb: [Ich möchte bezahlen.]

🇩🇪 At a counter, [gerne] often means "certainly" or "gladly," not just "with pleasure" in a warm personal sense. Staff use it a lot to keep things polite and efficient.

💬 [wohin] asks about destination, not location. Compare [Wo sind Sie?] for "where are you?" and [Wohin fliegen Sie?] for "where are you flying to?"

💬 [Sie] takes the same verb form as [sie] (they): [fliegen], not [fliegst]. You'll see the same pattern in [Kommen Sie?], [Haben Sie?], [Sprechen Sie Englisch?]

🇩🇪 At an airport counter, staff will normally use [Sie], and you should too. Using [du] here would sound too familiar.