Consistency matters most
Mixed values such as google, Google, cpc, and paid can split reports. Decide casing and separators first.
Use carefully on internal links
Too many internal UTM links can overwrite the original acquisition source. Prefer UTMs for external campaign links.
Case differences split your campaigns
Analytics treats UTM values as case-sensitive, so Google and google become separate sources and your reports fragment. Agreeing on lowercase and holding to it is the only real fix.
Never tag internal links
UTM parameters on links inside your own site break the session and register a new acquisition, erasing the original source. Tag only links arriving from outside.
utm_content versus utm_term
utm_term was designed for paid-search keywords, while utm_content distinguishes creatives within one campaign. For an A/B test of two banners, split them with utm_content so per-creative performance shows in reports.
