A very simple guideline I use is what type of customer service would I like to receive myself?

So, I

* try to respond to email quickly.

* don't write email like it's a press release.

* don't write too formally.

* issue "refunds" (for iPhone apps, I have to pay for Apple's cut). It's troublesome. I have to pay instead of refund. Some people have PayPal, some don't, Some have Amazon accounts, some don't.

* treat the party at the other side as a human, like I want to be treated.

* build a good product, and keep it good

it's surprisingly easy.

So next time you are at the receiving end of good or bad customer service, note it down.

PS: We really need Markdown or something similar.