Be Intriguing

Think of all the intriguing stuff about yourself then when speaking to him work it in amongst wit, some compliments and genuine interest. Be soft and sweet and you can be garaunteed that he will find himself thinking about your conversation.
Or to deal with longstanding attractions. Subtly hint that you have feelings or maybe make it blatantly obvious. Then after a while pretend to lose interest, it is a good way to have him really realise how much he'd miss you.