Some of the other things you can do are:
1) keep them informed, new products and services;
2) help them be a success in their business;
3) handle complaints quickly and follow up;
4) get referrals.
Depending on what your business does and what your customers need and how you sell to those customers, there may be more items on this list.
We have always offered several Customer Relationship Management software solutions like Sugar CRM.
Now we have a new solution called Bitrix24. You can watch a short video to see what it can do for you at http://youtu.be/N6K3udpfEOA
If you are one of our subscribers (even with just a free listing on Explorer4Philippines.com or one of the other Explorer4 sister sites, we will setup Bitirx24 for you, also for free. Small Businesses with less than 10 users can use 100% of the great bitrix24 software online, with no software to install and ample training available to hep you improve your relationship with your customers.