Here’s my suggestions:
1. Utilise Keyword Explorer to show them that there’s search volume for their products and services. This will show clients that it’s worthwhile investing in SEO.
2. Utilise the new Link Explorer to show that they need to continually build up high quality, relevant backlinks.
3. The on-page grader to show target pages aren’t up to scratch
4. You could even do a quick crawl and run the audit tool however you need to take each issue into context before mentioning anything to a client. This tool will help you convey their technical SEO health.
Personally for me, it’s that keyword report which is the most valuable to start with in the pitching stage as it really shows if an investment is feasible on their part.
When possible I also try and show where they are compared to competitors too.
Thats my two cents, hope it helps!
Cheers,
Casey

While only a small ranking factor, it still counts and can be very helpful for showing up in image searches.