Question
I've read a lot of different growth strategies that have worked for other companies; which makes perfect sense why they would work, for example:
Dropbox - I think they did a great job because they incentivized users to refer other users to get more space. And this worked well for them because by giving away more space this had an incremental cost of basically zero so this made sense.
Barkbox - People looooove their pets, so it's easy to see why these customers post so many images of their pets and Barkbox has such a high engagement on Facebook.
My website is an international shipping service website, so the only thing my customers care about is to get the products they are eagerly waiting for. So the only thing I see worth giving them that they would be excited about is "free shipping" to incentivize them to refer friends. However, in my situation I have a lot higher costs of giving away a "free shipment" than Dropbox had in give users 500MB more of space.
I've been trying to think of different ways that are not-forced but natural engagement to have my customers / fans be excited in sharing and telling friends but I can't seem to visualize an exciting angle like Dropbox and Barkbox had to work with.
Answer
I know this is a tricky problem to solve on optimizing costs and trying to get customers refer your service.
Referral schemes work perfectly where incremental costs of adding additional service is marginal, like the case of DropBox.
When the incremental costs are a significant portion and adding additional service is going to impact your CapEx, you need to identify the portions of the service which can be given away with less cost. So in this example, how about a free last-mile delivery for the next shipment for every friend who refereed your service to their friends? This won't hurt your bottom line a lot but brings up the top line.
Another way is leveraging the social angle associated. When someone is shipping a good internationally, the next thing he want to do is tell people about their sharing. Can you actually integrate social channels to your service, so that they can share it with world easily.