Let's face it: you're bad at this whole "romantic affection" thing. Really, that's being generous. You suck abysmally at it. Still, you've found yourself in something resembling a human relationship, somehow, and you feel like you either have or want to show you care. Uhm, congrats. I'm sure this is going to work out well for you!
Just kidding. Be it a physical gesture, kind words directed their way, or a gift, you're going to screw this up, most likely. Screw it up badly. Hopefully, they'll be charmed by you at least trying and won't be offended.