Apologies for the very vague question. I'm unsure of how I'm supposed to address and talk to children - I imagine it varies a little depending on the social situation, and in general I should avoid potentially awkward language as much as I should around adults, but does anyone have any broad guidelines? A few particular things I might fret about:
- Should I address a child I don't know with 君【きみ】? If I know their name, is [surname]+君【くん】 / +ちゃん usual?
- Presumably I should generally use plain verb forms rather than polite verb forms. Does this change if I'm talking about their family members or similar (or indeed ever)? Is it usual to give commands with ください, ～なさい, くれ or just plain ～て form? (I'm unsure of whether なさい is too blunt - my intuition about this word is that it's one used when the speaker is in the same social hierarchy as the listener, but higher up. This probably applies if I am a teacher or a parent, but not if I meet them in the street.)
- Do I refer to their family members as お父【とう】さん, etc.?
- If I give them something, do I あげる it to them or やる? (The latter feels rather blunt to me.) If I talk about someone else giving them something, do they あげる, やる, くれる or くださる it? (I would guess くれる sometimes occurred in the case of very young children - though this doesn't feel like a linguistic issue! - but otherwise あげる or やる according to what the 'giver' would describe it as?)
- At what point does a child become an adult (in the sense of addressing them with さん and/or using polite verb forms)?
- (A final, less general question. I tend to use 僕【ぼく】 to refer to myself, but have heard of adults referring to young boys like this. Would this be confusing? How should I refer to myself?)
(The context is that I (male, mid-20s) encountered a young (8-ish?) Japanese boy yesterday - actually, he spent 45 minutes thrashing me all over a goban - and would have liked to exchange a few words of congratulation, but as his father was present I was a little nervous. I wasn't sure whether using forms like ～なさい and やる would have implied I thought very highly of my own social status, but I also wasn't sure whether using forms like ～ください and あげる was a little heavy towards a young boy, who may never have been spoken to directly like that. Still, I'd be very interested to see the question answered from a general perspective.)