I was a bit more confident in my youth and did this kind of thing a few times. The note with phone number is easy, al you have to say is 'Can I give you this?' and walk away. What's the worst that could happen? He doesn't ring? Either way he'll be very flattered and maybe even grateful.
I did this to a waiter at a wedding (put my number on a napkin), he phoned and we had a few nice dates.
I did this to a bloke digging up a road - I was passing in the car and thought he was gorgeous - he never rang! But hey, you're not going to get lucky every time.
I looked up the e-mail address of a guy I fancied in the uni directory and sent him an anonymous message of admiration. It turned out he was engaged, but we had a nice, friendly (not flirty) e-mail exchange for months afterwards, it was a good laugh.
I sent a Valentine's card to the biggest, 3 yr long crush of my youth - I mean it was bordering on obsession from when I was 14 to 17. I put my e-mail address down and he replied. we went on a date and it was awful, he was awful, sexy as f* but such a nasty guy, spent the evening telling me about all the times he'd cheated on his girlfriends, which ones he made have abortions etc
. Still, at least I got closure on that one...!
Most recently I sent a text to the cute guy from Britain's fourth emergency service
who fixed my car the other day. The exchange is currently heating up! It's the first time I've done anything like that in years, I am not a big flirt at all and in fact haven't been on a date in five yrs (since becoming pg getting dumped and living as a single mum for ages). Most of these I did when I was younger but might still do, they are all fairly anonymous and thus psychologically 'safe'.
It's only really Britain where this isn't the done thing I know in most of continental Europe men don't think twice about approaching a woman they like (maybe vice versa? I don't know), and I've heard in New York it's really common to ask people out (men and women) just from seeing them and liking the look of them, with no prior small talk. Save that for your first date!
Good luck! If you have been exchanging looks for 6 months he is probably on 'blokesnet' at this very moment posting a similar message about you!