I don't think subtly is a wise choice in this situation. If your date does not take the hint, your feelings may be hurt and he will not understand why. I believe it would be best to simply tell him that you would like for your corsage to be (for example) blue and white. Women tend to be subtle and use hints in asking for what they want or need. Men tend not to understand hints. It may not be comfortable at first, but learning to be direct about your wants and needs will save you a lot of heart ache.
* Corsages are generally for special occasions such as Graduation, etc. Instead of the old way of pinning a corsage on a girl's dress there is now the bracelet corsage which is easier for the girl to wear (just puts it around her wrist.) Just tell the florist what you want and it's always nice to be sure the flowers go with the color of the girls dress. If you aren't sure of the color of her dress then tell the florist and she will make up a nice bracelet corsage with a more neutral color. You give the corsage to your date when you enter her home to pick her up. The corsage generally comes in a small box with plastic on top so she can see it right away and either she will take it out of the box and place it on her wrist or you can do it.
Just subtly tell her "wow, you look nice today"
Be honest and tell her, if you mean subtly I’m not sure myself.
When your talking with him tell him about the formal and tell him you would love it if he would take you.
...ask one of his friends (if you are their friend also) to ask him subtly
Well personally I would but to make sure I would talk to other girls going to see what they are doing because it changes depending on where you live and what people think.
How can one tell whether the salutation or complimentary close is formal and impersonal?
be formal.
It depends if you consider them a friend. If s/he is an acquaintance, tell them politely that you think they are rambling. If they are a stranger, walking away subtly may be the best course of action.
tell = hELu (informal) tell = hELi (formal)
Tell him to join you in something and just tell him its not a date
Because, they used a sundial to tell date and time.