(Klar, Englisch ist die Weltsprache Nr.1! Deswegen sind Englischkenntnisse so wichtig, und nicht nur in der Touristik.)

Even tricky corporate communications like brochures, websites, annual reports or sales proposals?  

(Naja...auch manche "Native-Speakers" haben damit ihre Schwierigkeiten...)

Think before you publish:
Are you sure the English is correct? Is it good English?

• Who will see your text? Is it anybody important to your business?
  
• Will your readers notice the mistakes? What will they think, if they do?
• Are you sure the tone and style are appropriate for your audience?
  
• Have the words been used correctly? Are they the right words for your purpose?
  
• Does your intended meaning come across?
• Does the document make the professional impression you want it to make?

Wouldn't you prefer to have a highly-qualified native speaker check it over first? Or perhaps write it for you in the first place?