Signing up customers is the first battle, but keeping them happy is just as important. Below, founders share their advice for maintaining those relationships--and never turning into those big cable companies that people love to hate.

1. Let them go. Make it easy for people to change their preferences or cancel the service, so they don't leave angry. "It engenders a negative brand perception if you make customers pick up the phone and wait in line to stop paying you," says Michael Dubin, CEO of Dollar Shave Club.

2. Talk, don't sell. Between transactions, send your customers emails and magazines that offer relevant content without sales pressure. "Customers get tired of being asked to buy all the time," says Nick Taranto, co-CEO of Plated. "And if it's great content, it can drive referrals."

3. Lock down their data. Data breaches are headaches for all kinds of retailers--but cybersecurity is especially important for subscription-based businesses, which keep credit card data and home addresses on file. "Privacy is super important," says Taranto. Plated uses tokens for all of its sensitive information, so that it can store the actual data in a more secure environment outside its own systems.