Is it a Pay per Click or PPC campaign? If it is, then it will definitely depend on the bid rate you have on the keyword you choose you will pay more for popular keywords . If you properly managed this campaign your click through will increase and expect to have higher chance of conversion to those who actually become customers.
The appearance of your ad is dependent on the amount you bid on that keyword. The more competitive the keyword, the higher the bid rate. I suggest you opt for long-tail keywords, for they target specific audience/consumer, making the campaign's conversion rate higher.