I wanted to mention to a female staff member in a shop that I visit every day that I had seen their photograph in the Shibuya shop. I was going to say:
渋谷店であなたの写真を見た。
..but あなた seemed too intimate. If I knew their name, I could have said, for example:
渋谷店で田中さんの写真を見た。
..also きみ seemed too casual.
渋谷店で君の写真を見た。
What is the most natural way to refer to someone when you don't know their name and don't have a close relationship with them?
By job name: 店員さん (clerk)、お巡りさん (bobby)、運転手さん (taxi driver), etc. Polite: そちら (which I prefer to あなた which may sound informal in some situations),
Girl: お姉さん【ねえさん】
Boy: お兄さん【にいさん】
Man: お父さん【とうさん】、叔父さん【おじさん】,
Woman: お姉さん【ねえさん】、お母さん【かあさん】、叔母さん【おばさん】 (this one is dangerous!),
Elder people: お爺さん【じいさん】、お婆さん【ばあさん】.
Best way: ask for the name.
Best way to ask for the forgotten name: ask for the kanjis of the name :)
But I agree, it takes a lot of practice to naturally think of a way to call out people…
Regarding your particular situation, I think Axioplase, Mark and Istrasci have given you all the options you really need. By order of smoothness, I would go with:
skip name
あなた (as Mark says, there's a bit of cognitive dissonance between the two uses, but it still works)
whatever else...
To answer the more general formulation of your question title, I would add one that I personally found a lifesaver in many similar situations. For people you want to be polite to, but don't want to use 'あなた' with, for some reason:
そちら
While it is not ultra-common use and practically keigo level of politeness, it is still somehow neutral enough that using it in semi-formal conversations (typically in my case: people slightly older/higher, whose name I forgot and whose meishi I misplaced, but for whom あなた sounds a little too precious) is perfectly alright.
Edit: A very typical way I would use そちら, is if, after making a sentence omitting the subject (my first choice), there is an ambiguity and/or misunderstanding. As a way of saying "you [not me]".
@Axioplase gave a good general answer, I even +1'd it. @istrasci was also correct in that you can avoid saying "you" and instead say "you're the person in the photo..."
However in this situation I think it would be natural (and smooth) to read her name off her name badge.
If you can read it: confirm the reading with 「XXさんですね...」
If you can't read or she doesn't have one: just casually ask 「すみません、お名前は？」
As a customer, you are in a superior social position (お客様は神様でしょう) so being polite yet a touch casual is appropriate. You don't want to be rolling out your best keigo here.
Once you know her name, you can mention you saw her picture elsewhere, using @YOU's example would suffice here: 「ちなみに、渋谷で XXさんの 写真を見たようですが...」
Good luck
NB: This question is borderline なんぱ, but how better to learn a language than by using it? *grin*
あなた has two usages. One is used by spouses when talking to their spouses and translates as "Darling"
However, it is also can be used when you don't know the person all. In this case I would think that Anata would be perfectly usable in this case. And in fact would be too cold if you've been seeing them all the time recently. Then again if you haven't actually asked her name, I would stick you in the outsider group and still use Anata.
I think 渋谷店であなたの写真見 ましたよ works properly in that situation. Basically あなた goes with です/ます. The level of intimacy of expression can be controlled by the level of politeness. So, you can say much more politely and safely, 渋谷店であなたの写真を お見かけしました.
Dropping あなた will also work, such as 渋谷店に貼ってある写真を見ましたよ.
However, 君 is definitely too intimate (more intimate than あなた) and using her personal name might sound like a stalker if she has not told you it yet.
