Evaluating the performance of your ad is always a good way for optimising your campaign. You will need to configure conversion tracking on your website if you planning on generating leads, enquiries or sales when someone clicks on your ad so that you can evaluate the performance and the clicks from LinkedIn.
If you are planning on generating more leads or sales you should ensure that your ad is targeted at people that are in the locations where you do business.
You should also ensure that the landing page from your ad is the best and most affective page for your customer to land on. The information on the landing page should relate to what you are offering in your ad. If you are planning on generating more awareness about you business you should try testing more images to see what is most effective, these images should relate to what you are offering in your ad.
People who click on your ad can request for you to contact them in regards to what you are offering if this feature is enabled. When a request is sent you will be able to see the members name, headline, a link to their profile and possibly an email address if they chose to. If they have given you their email address you will then be able to send a follow-up message to them for free on LinkedIn.