Is there any relief to ST Data/Google My Business verified/etc. calls?
Reddit
Getting More Google My Business Reviews
If you have a core of clients that you have a strong relationship with then those are your ones to ask first. Send them a 'somewhat' personalised email and be honest - Google reviews really help your business so it would be hugely appreciated if they could take a minute to leave a review. (you can send a link direct to the review. Google generates this for you somewhere...)
If you don't have a core of return customers then you could look to set an automated email that sends a set time after a client has purchased from you...? Mailchimp can do this depending on how your systems are set up. Hard to know your best options without knowing more.
Basically... Just ask. If you know you are nailing your customer experience/your product is on point then you have nothing to fear.
I'd steer clear of offering discounts in return - I think it comes across as desperate or possiblely even underhand/disingenuous... IMO.
Good luck
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