Men are surprisingly tactile creatures; they love to be touched, to be held and to be kissed. It's a reassurance that you want to be around them and you want physical contact with them. Showing affection to a man is the best way of telling them "I want to be around you and I want to be close to you".
When you come home from work, before you tell him all about your day, give him a kiss and tell him you missed him, and how happy you are to see him. It will make him feel wanted and secure, and that he's more important in your life than little concern that goes on away from him. Affection can take many forms; kindness, warmth, reassurance and support. Never miss an opportunity to your man and notice how much he loves receiving it.