The strongest local ranking signal you can influence.
WHY THEY MATTER
Reviews affect both whether you appear in local results and whether someone chooses you over a competitor.
A business with twenty reviews is chosen over one with none, almost regardless of what else differs.
GETTING THEM
Ask. Most satisfied customers will oblige if asked directly and shown how. Ask soon after the work, while the experience is fresh.
Make it easy: send a direct link.
Ask consistently rather than in occasional bursts.
WHAT NOT TO DO
Buy reviews. They are detectable, and the penalty is worse than having none. Write them yourself. Offer payment for positive reviews, which breaches most platforms' terms. Ask only customers you know are happy, which is against the spirit and usually the rules.
RESPONDING
Reply to every review, positive and negative.
For criticism: acknowledge, address the specific point, offer to resolve it. Every future reader sees your reply, and a calm specific response reassures more than the complaint discourages.
Never argue publicly.
CONSISTENCY
A steady trickle of reviews over time is more credible than twenty appearing in one week.