Negative keywords are an excellent way to eliminate irrelevant impressions and improve the quality of your PPC traffic. They help boost your CTR, improve quality score, lower your CPCs and increase ROI. Here are my 5 best practices for using negative keywords with Google AdWords:

1. Use negative keywords at the campaign level. Negative keywords in Google AdWords can be applied at the ad group or campaign levels. In most cases, you’ll want to use them at the more scalable campaign level to eliminate specific words or phrases from appearing with any on your keyword combinations pertaining to your entire campaign.
2. Use the AdWords keyword tool. Look up additional keyword variations for your highest impression generating keywords through the keyword tool. Any searches that are not relevant to your business should be added as negative terms.
3. Expand your negatives. Make sure that you expand the negative terms you come up with, adding singulars, plurals, synonyms and any other variations you can think of. The Google AdWords system does not expand the negatives for you. For example, if you’re running on a keyword ‘cosmetic surgery’ and you add a negative keyword ‘pic’ the query ‘cosmetic surgery pics’ still might trigger your ad unless you add ‘pics’ as a negative as well. Add synonyms (photo, photos, picture, pictures, pix) while you’re at it!
4. Run search query reports. Search query reports will show you actual queries that led to clicks on your PPC ads. Any queries that do not apply to your website are excellent negative keywords. I recommend running this report once a week.
5. Use advanced negative matching options. In addition to negative broad match, you can also use negative phrase and negative exact match. Negative phrase and exact match should be used to restrict specific phrases from triggering your PPC ads, but still preserve and allow your PPC ads to be triggered for some of the words within that phrase. Let’s say you are advertising a cosmetic surgery website, and you’re running on keyword ‘breast enhancement surgery’. Here are some use cases for advanced negative match types with that example in mind: