I've always had sticky notes, not only in the office but also at home and in my bag. One common problem of sticky notes is cause by pulling it off in the wrong way. Most of us will pull it from the bottom to the top and this results the paper to curl when we stick it.
The trick here is when you pull the paper, it should be on the left or right side of the top pad. So when you pull it, the paper will not curl. It is flat when you stick it down.