Sit and chat while looking at him, or at least concentrating only on him - no ds, no tv, no screen.
At random moment, just say 'phwoar you look gorgeous today love, you have such sexy [shoulders]' or whatever (shoulders probably my thing, ignore that)
sit at his feet and give them a massage - haven't done that one for a while, might do it tonight
give him a lie in and make no hints about when i'm getting one
take a lie in for myself, don't give any instructions and tell him how great he has made me feel
decorated the house with a big banner and bottle of wine when he passed his exams
ring my mum and tell her how proud i am of him, how much he's been doing for me, in front of him
ask him what he's thinking - but my dh is possibly unique in genuinely liking to be asked this, it's taken me 3 years to get used to it