I’m (33m) an average looking guy who keeps screwing up dates with very attractive women

I've been chatting with this woman (28f) for a few days now and it's been great. Probably the best chatter I've ever met. Got a lot in common etc.

I've had this before and I'm always myself on the chat but once I saw some more pictures of this woman I'm absolutely sure that in real life I'll be completely blown away by her, and I need some tips on staying relaxed and staying me.

We're going for a walk this Tuesday so I can keep my eyes on the road rather than her, because boy is she a knock out.

Anyway, tips would be great.