150-155 characters, include the target keyword, a clear outcome, and a call-to-action. Avoid sensationalism; match FCA fair-clear-not-misleading rules.
Formula
[Keyword-rich outcome] + [credential or proof] + [CTA].
Example
"Chartered mortgage adviser specialising in self-employed cases. Whole-of-market access, transparent fees, no-obligation review. Book your consultation."
Dont
"BEST mortgage advice - FREE!!! Guaranteed lowest rate!!" - fails compliance and Google guidelines simultaneously.