The way to get reviews is to ask every happy customer, right at the moment they are happiest. A text with a direct link beats a card with a QR code, and both beat hoping.
Volume and recency both matter to local rankings, but so does your reply. Answer every review, good or bad, in a sentence or two. Future customers read the replies, not the score.
Never buy reviews or offer perks for them. Google catches it, and one penalty costs more than a hundred honest reviews earn.
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How to rank on Google Maps The Google Business Profile checklist What is local SEO? More about Local SEO setup