One thing that has become as common as a mobile phone number has got to be an email address. It is a rarity to hear someone say they don't have email, just the same as if they said "I don't own a mobile phone" and it is why you need to be compiling a list.
Often a potential customer will provide an email address willingly before they sign-up to pay for your product or service so they can start to get a feel for what your business is all about and they may have had you recommended by a friend who has used your business, maybe they heard you have previously offered discounts or special offers and they are waiting for you to repeat this offer.
So you owe it to current customers and potential alike to keep a contact database and consistently reach out to them with updates. It can be as simple as a monthly email newsletter and it really doesn't need to be long. You can even build a yearly calendar and do some of the leg-work early or even repeat it. e.g.
January - Welcome to X Year from all of us at (company)
February - Could your business target Valentines Day or special offer?
March - Easter Holiday offers
and so on...
Think about Holidays in each month that suit your business offering and/or client needs. What about your yearly specials like a stocktake clearance or spring cleaning, closing for holidays or other important dates. Set email dates for these and if necessary, alarms in your calendar to finalise messaging.
Then think about opportunities to collect email addresses like on your website and social media - Facebook can add a mailchimp signup tab for instance.
We recommend using mailchimp. It is a brilliant free service is you have a small list, but they also have some incredible paid functions like automated emailing, so you can spend a little time at first planning these out and then set-and-forget like: email offer to new subscribers say after 60 days with a special offer code and thank you message for being a subscriber. Or you could set up an automation for anyone that clicks on specific links indicating an interest in certain areas of the business, it could be a series of information based communications. What you ideally want is a range of content that you can repeat across platforms.
Remember that this email list is a list of people that have indicated an interest in your business. They are your customers so think of ways you can reward and excite them with offers from your business. It's a win win situation.