In each app I develop, I like to add three types of messages:

• Green/blue for success messages
• Yellow for warnings
• Red for errors

And perhaps, a neutral one for information, which is gray or blue if the success one is green.

The success one is used for when an item is created or updated, the yellow one is when there's something wrong, but not we-are-going-to-die wrong and the red one is when something is blocked or we are going to die.

However, there's one thing I can't figure out, when I delete an object, what kind of notification should I use? I think the success one is not because it is not expected, altough the deletion was successful, the user tends not to read the message, just to see the color.
The red one might be, but it can be misunderstood (I tried to delete it but there was an error), the warning and the information one might be good choices, but I'm not really sure.

Also, when you ask for confirmation about deleting something, the 'cancel' button should be green or red?

I'm just curious how you guys handle this. Thanks.