Thank them for something they did for you that day.
Initiate a random act of affection
Clear the slate, apologize to your partner if you have done or said anything that upset them
Indulge in a sensual kiss (must last at least 10 seconds)
Compliment your partner (see 10 ways to compliment a man)
Talk to your partner for at least 30, uninterrupted, minutes
Bonus: Do something romantic for your partner