As simple as this sounds, all the elements of being a supportive family member are in this gesture; staying in touch, letting them know you are thinking about them, showing interest, and being encouraging. The little things do mean a lot. Students check their mail boxes everyday; often they are empty or just have junk mail in them. Even if you live close to Western or call them frequently send a funny card to them once in awhile.
Do not underestimate the benefit of regular email or letter exchanges with your student. Written communication differs a great deal from phone calls. Your student may have an easier time communicating some things they are nervous about in and email rather than over the phone. It is nice to be able to "reread" how much your family loves you expressed in an email. And easier at times for your student to say "I love you" in an email rather than on the phone when all their buddies are around.
The final tip: let your student know when you are coming for a visit. As glad as they may be to see you they may have plans with friends that they don't want to break. They also may feel awkward or uncomfortable about you unexpectedly appearing in the environment in which they have established their independence.