Asking customers to share your shop works about as well as asking them to leave a review, which is to say it works when there is a reason and not otherwise.
What it does
A share block the customer can use from their account, offering the usual destinations plus email. Using it earns them something.
The important detail is what gets shared. Every share is built around that customer’s own referral link, not a plain link to your homepage. So the share does two jobs: it earns the customer a small reward now, and if somebody arrives through it and orders, it earns the referral reward as well.
Sharing and referring are the same system rather than two competing ones. The share is how the link gets somewhere; the referral is what happens when it works.
Rewarded once, not repeatedly
Share bonuses are limited so a customer cannot sit there clicking the button to farm points.
This is the obvious failure mode of any share incentive, and any scheme without the limit gets found within days of launch. Paying once for the act, and then paying properly for outcomes through referrals, puts the money where the value is.
Why pay for the share at all
Because the outcome is uncertain and the action is not.
A referral reward only pays when a sale happens, which is correct but means the customer takes a chance on getting nothing. A small, certain reward for the share itself is what gets them to do it in the first place. The referral reward is then the upside for both of you.
Paying a little for the action and a lot for the result is the right shape.
Where it goes
A shortcode, so you can put it on the rewards page, after checkout, in a thank-you email, or anywhere else a satisfied customer is likely to be.
Immediately after a purchase is usually the best moment. The customer has just decided they like you enough to buy something, which is the peak of their willingness to tell anyone about it.
Off by default
A feature toggle. Sharing prompts are an addition to your customer-facing pages and switching them on should be a decision.