Advice on declining handshakes and hugs with non-mahram

Assalamu alaikum, I’m really struggling with this. In the moment, especially with teachers or when greeting a group, I freeze and can’t pull my hand back or politely refuse handshakes and even hugs from the opposite gender. It’s like my body moves on autopilot and then I feel terrible afterwards. Has anyone found a way to handle this gracefully without making it awkward? JazakAllah khair for any tips.