A mistake a lot of advertisers make is not using exact match keywords in their campaigns.
With an exact match keyword you have full control over that keyword, over how often it shows up, where it shows up and how much you pay for it. Now granted you can just decide how much to pay for the keyword – there is still going to be competition. But relative to your competition, you’re going to be able to really control your bid price to the level that’s most profitable for you, that’ll give you the most volume compared to your profits, and you can figure out the most profitable way to bid on that keyword.
If you don’t have exact match keywords and you are relying on other keyword types to do the work for you, the problem is: If you have a broad matched keyword there are actually going to be hundreds of keywords showing up just for that one keyword that you have. So it’s impossible to control the bid, because one keyword might require a bid of $5, and another keyword that’s been matched with that same broad keyword might only need a bid of $1. So now, even though one keyword requires $5 and the other requires $1 to get in the same spot, you’re bidding on those exactly the same because they are broad match keywords.
As much as possible, you need to look through your account. Find the keywords that are generating the most traffic for you, find the keywords that are converting well, and start adding them as exact match keywords.
The more exact match keywords you have, the more control you will have over your campaign.