Which three campaign parameters are recommended to manually track campaigns?

If your Analytics account is linked to an active Google Ads account and you have auto-tagging enabled, you don't need to tag your destination URLs in Google Ads. However, for example, if you run paid search campaigns on search engines other than Google, you'll need to tag the destination URLs for those ads. To manually track campaigns you you generally need to use only Campaign Source, Campaign Medium, and Campaign Name. Tip: Keep in mind that there are more parameters which are useful in specific cases. However, it’s prohibited to send sending personally identifiable information (PII) to Analytics, such as names, social security numbers, email addresses, or any similar data.