You either charge per hour... or a flat-rate each month, that is payable at the beginning of each month.
$10 per hour... is a low amount. Students get that pay.
You are a "Mom" with experience.
But she is your friend.
I would not though, go lower than $10/hour.
What does she pay now, for Daycare?
And, I would have mutual 'rules' on your care..... paying on time.... and if she is late for drop-off or pick-up, she HAS to let you know, ahead of time etc.
It is just courtesy and she is a friend... so friends should respect that.
AND are you supposed to provide meals or not? Diapers or not? Naps?
And what kind of care does she expect?
ie: teaching them school prep? Just watching them and their safety? Taking them out in your vehicle??? If so... then WHO is going to provide her kids' car-seats etc.?????
And if you take her kids out in your car.... you should have her sign a release-of-liability etc. Still. Even if she is a friend.
"Baby-sitters".... are really people who don't get paid much, considering what they do.... and it is very hands-on and laborious.
all the best,
Susan