Before trying to save money on your AdWords campaign you need to identify where your problem is. You need to get your search query history in front of you. Now look at the keywords that have click but no conversions. You will want to remove these keywords from your campaign. Also check for other themes or keywords that may have led to a conversion however it does not match your goal.
You can start eliminating useless traffic by using negative keywords. Look at the type of searches performed that result in clicks that don’t convert to customers. If you notice a word appears often amongst those searches make it a negative keyword. You can also modify these negative keywords. It can either apply to an ad group or the whole campaign. You will have to decide which route to take depending on the type of ad/campaign. The negative keyword uses the same match system and normal keywords. So you have to manually select the keywords that are negatively impacting your ad campaign.
“Keyword” – Phrase match: will eliminate any search containing the keyword.
(Keyword) – Exact match: eliminates only searches of only that keyword.