I would like to know some closure formula for both formal and informal letters. I'm a beginner, hence I know only the classical and easy
Viele Grüße, bis bald!
for informal letters. I am looking for some other polite formula; indeed, how can one say "Look forward to hearing from you soon"? Is it something like
Ich hoffe, bald von Dir zu hören.
What about formal letters? I thank you in advance for your help.