For women with fair to medium skin a sure fire way to tell if she is aroused is to look at her ears as they will go a very distinct pink and it is something that they cannot consciously control, you can see a good example here
https://forum.oneclickchicks.com/atta...9&d=1334667005
Also for most part they should have their eyes shut or only just open but this may vary with the surroundings e.g. in the bedroom is very different to in the park in the daytime.