Be sure and keep an eye on your average position with your Adwords keywords. There are times that it is going to pay (pardon the pun) to either increase a bid or drop a keyword that is getting hits, but is falling in position.
In one campaign the competition was fierce and my ad text wasn’t pulling. Over time the position continued to fall and I received less clicks. After reviewing the money it would take to move up, it wasn’t worth it. I dropped the keyword and moved on.
The key is to be brutally honest with yourself and your keywords. If you’re not pulling and you have tested ad copy sufficiently, cut the dead weight.