Never Give Up, Never Surrender

Three campaigns are working to persuade advertisers to pull their ads from "news" websites that promote hate in their stories. Often advertisers don't even know their ads are appearing on the online versions, as they're served by intermediaries, but there are simple ways to prevent their ads being placed on particular sites.

Sleeping Giants/slpng_giants is specifically targeting US advertisers on Breitbart.

Sleeping Giants EU/slpng_giants_eu is targeting European advertisers on Breitbart and is actively looking for help to identify advertisers whose ads are being served in each European country.

Stop Funding Hate/StopFundingHate is a UK-based campaign targeting three newspapers, the Sun, Daily Mail and Daily Express, which constantly run hate-mongering stories (and have been criticised by a statement from the UN for doing so).

Instructions for how to help are pinned at the top of each twitter stream but are similar:
1. Screencap the ad on each site (or snap a photo of a paper copy) next to some editorial copy
2. Tweet the screenshot at the advertiser, copying in the campaign, and politely ask them if they know their ads are appearing on this site and ask them to stop
3. Update the campaign

There are plenty of "scripts" for how people have worded their tweets on the twitter stream pages of the campaigns.