Why can't I ever say the right thing????

I am really starting to get fustrated with myself. I have the tendency to whenever people tell me important things I just think oh my gosh did they really just say that and I never respond. Like the first time this kid told me that he liked me, I didn't say anything. Yeah I am werid and the worst part is that I really like this kid. I don't know I just freeze when people tell me things like that. After he told me that he liked me he also said that I was very distracting and of course I didn't say anything to that eaither. It was kind of like he was trying to get it out of me and believe me I wanted to tell him but there was some part of me that couldn't. I can just never say the right thing when the opportunity presents itself. After I have had the conversation with someone I always think of the perfect thing that I should have said but by that time it would be akward to bring it up. Oh well I hope I become better at saying what I want when I want.