When designing mobile advertising campaigns, what is a best practice to identify which keywords to target?

The Answer of this Question : When designing mobile advertising campaigns, what is a best practice to identify which keywords to target?

• Ask your audience what they search for when looking for similar products
• Use the Google Keyword research tool or Bing Keyword research tool
• Use a tool to harvest the keywords your competitors are using
• Use all the usual keywords from your website in your advertising account