A small bitte or danke goes a long way:

German	English
Bitte.	Please. / You're welcome. / Here you are.
Danke. / Danke schön. / Vielen Dank.	Thanks. / Thank you. / Thank you very much.
Gern geschehen.	You're welcome. / My pleasure.
Entschuldigung!	Excuse me! / Sorry!
Wie bitte?	Sorry? / Pardon? — when you didn't catch something
Herzlich willkommen!	Welcome!
Freut mich.	Nice to meet you.

Bitte does several jobs: please, you're welcome (as the answer to danke), and here you are when you hand something over — often as Bitte schön!