So, not that I would ever do private teaching. First of all, it's illegal unless you have a certain visa, such as if you're married to a Korean. Second of all, I kind of loathe the 1-1 teaching and would rather just have a big class. Thirdly, I hate cruising 'round the city after my normal working hours and would rather just go home and relax and be done for the day.
But, if you're doing to do it, then for the love of all things, don't even consider doing it for free or for a ridiculous pittance! Like, a co-teacher or a co-worker asking you to hang out with their friends' kids on the weekend is actually private teaching in disguise. You should be getting paid for this. And at least 50 000 an hour to give up your weekend to hang out with kids that are not even yours. Or, at the very least your movie paid for and a nice dinner at Outback thrown in on top. You're worth more than free.
And one time, my old uni asked me to teach kids on weekends and the pay was 30 000 Won for 2 HOURS! Not 20 minutes. Yes, 2 hours. I'm worth more than 15 000 an hour, so I said no, of course not.
Or, teaching English at a Church or something. If the students are orphans, or abused women, or refugees from North Korea, or kids that come from single parents homes, then yes, of course you shouldn't ask for pay. But, if they are just regular old people who are business professionals, or teachers, or something? Or kids, whose parents are doctors are lawyers? Then, yes, you are worth more than free, even if you're doing it at Church.
Rant is over :)