Let people code their way

Don’t let yourself get caught up in your solution (or the perfect solution) when someone is trying to do something.
Imagine that someone has joined the channel, wanting to draw a line in Java2D. They have a question about the precision of floating point math, because they’re drawing the line manually, point by point, using slope.

Use your imagination here. Java2D doesn’t have a method with which to draw a single point; you have to draw lines that happen to occupy single pixels, so there’s no point to using slopes. It’s an example.

The temptation is to scream at them until they use Java’s built-in line-drawing method, or use the right types to get the precision they want, or… something.
Don’t do it. Tell them the right way to do it to the best of your knowledge, and let it go. They will make their own choices, and any consequences are theirs to bear, not yours.
On the other hand, if you’re the one asking questions, and everyone in the channel is telling you that you’re doing it wrong, you might do well to heed their advice – it’s not like the channel regulars don’t know what they’re on about.