What should I say to him ?

so I'm texting my crush and I think he likes me too.. he always looks at me and checks me out, and he always looks at my house, and at my bus stop he looks at me, then quickly pretends he's texting when i look up... and he texted me saying "yee" after our convo so what should I say to keep the convo going without sounding desperate or too flirty ?