Do You Have A Competitive Edge (The Most Important)?
This will be what makes you better than the competition. You MUST MUST MUST know this and be able to quickly and easily convey this before you start any advertising. There is a lot of competition on Google for pretty much everything. You need to be able to tell people why you are the choice so they can choose you.
Do You Have A Landing Page That Conveys Your Message in 5 Seconds or Less?
A landing page is where someone will go right after they click on your ad on Google. If you're thinking "I have website, can that be my landing page", the answer is NO. If you are going to spend money advertising on Google you should have a page made for exactly what you are trying to offer or sell. If someone is going to take the time to search for something, GIVE IT TO THEM right away, don't make them find it. If you make them find it, they probably will, just on a competitors landing page.
Do You Have The Proper Tracking In Place?
It does not matter what you do, if you cannot track the result your Google advertising you cannot improve it. All advertising has parts that are profitable and not profitable. Using proper tracking you or the person managing your Google account can quickly see what is working and what is not. Then pull money away from what is not working and move money money to what is working and making you a profit.