The type of campaign you should use for your retargeting strategy will depend on your specific goals and the type of business you have. Here are a few campaign types that can be effective for retargeting:

1. Display remarketing campaign: This type of campaign allows you to show image or video ads on websites within the Google Display Network to people who have previously visited your website.
2. Search remarketing campaign: This campaign type allows you to show ads to people who have previously searched for keywords related to your business on Google.
3. Video remarketing campaign: This type of campaign allows you to show video ads on YouTube to people who have previously interacted with your videos or channel.
4. Shopping remarketing campaign: If you have an e-commerce business, you can use this campaign type to show ads featuring products that people have previously viewed or added to their cart on your website.

When setting up your retargeting campaign in Google Ads, you can choose the campaign type that aligns with your goals and target audience. It’s important to consider the type of business you have and the behavior of your target audience to determine the most effective campaign type for your retargeting strategy.