Think like a customer.
What terms or phrases would your customers use to describe your products or services? List any keywords that you think users might search for on Google to find your business. Then expand your list to include relevant variations including alternate spellings (e.g. light, lite), plurals, and synonyms.
Refine your keyword list.
Keywords that are too broad can lower your performance by generating many ad impressions but few clicks. For example, using the generic keyword bags to promote luggage goods could show your ad to users searching for unrelated items like tea bags and vacuum bags. To make your keywords more specific, add words that are descriptive of your goods or services. Instead of using the keyword bags, try more relevant and descriptive keywords like "luggage bags," "carry-on travel bags," and "buy luggage online."