What do I mean with relevancy?
When creating ads and adding keywords, more often then not I see people making mistake and not connecting the specific keyword to a specific ad. To simply put, relevancy in ads is that each keyword you are targeting has to be used and inserted into the ad text, preferably in the first or second headline (Header 1 or Header 2).
This means that, for each keyword we are targeting, we will create a specific ad that contains that keyword in the Ad copy. So if someone is searching for a "residential electrician", and you are targeting that specific keyword, you must create the ad that contains "Residential electrician".
This connection between keyword and the ad is necessary because when people see what they are looking for and click on your ad, Google will reward that by giving you a better quality score which will eventually result with a lower cost per click. O n the other hand if your ad is not relevant to a search query, guess what, your cost per click will be higher.
In addition to this, your ads must be more attractive and interesting than your competitor ads, so you have to make sure your ads stand out. When you achieve this, people will click more often on your ad and this way your ad gets a higher position because of higher click-through rate (CTR).
2. Landing page
This is also a very important factor and everyone who clicks on your ad must land on a relevant landing page. For example, if someone is looking for a "commercial electrician" and then see an ad where it says "Commercial electrician", then they click on that ad and land on a page where it says "Residential electrician", they will bounce off.
So even if this company offers commercial services anyways, the visitor will feel that he is on the wrong page because he was specifically looking for a commercial electrician. Also, depending on how long they stay on your website/landing page, this will be a sign if they are on the right place and Google will give you a quality score based on this.
3. Negative keywords
These are the keywords that you don't want to show your ads for. If you are not building your negative keyword list, you are essentially throwing money to the wind. In most cases, you will want to make sure to add negative keywords like "how to", "free", "ideas" and many more similar irrelevant keywords that you don't want to show up for.
The negative keyword list will be specific to the vertical you are in, but to give you a good headstart, I created a universal negative keyword list that can be applied to the most types of businesses. Feel free to copy those negative keywords HERE