If you take money online, in any way, you NEED to have an accessible and satisfying ‘customer service’ type page. Google says, “Contact information and customer service information are extremely important for websites that handle money, such as stores, banks, credit card companies, etc. Users need a way to ask questions or get help when a problem occurs. For shopping websites, we’ll ask you to do some special checks. Look for contact information—including the store’s policies on payment, exchanges, and returns. “ Google urges quality raters to be a ‘detective’ in finding this information about you – so it must be important to them.
In Keyword Planner, formerly known as the Keyword Tool, you can get search volume and traffic estimates for keywords you're considering. Unfortunately, when Google transitioned from Keyword Tool to Keyword Planner, they stripped out a lot of the more interesting functionality. But you can make up for it a bit if you take the information you learn from Keyword Planner and use Google Trends to fill in some blanks.
But be aware! You can’t just blindly trust the search results because Google tailors them to your personal search history, which means your site will come up higher for you than for others doing the same search. You can get around this by searching in incognito mode, although there’s still a local search component even in that. If this’s likely to be a problem for you, consider using a VPN to conceal your location.
Ask for a technical and search audit for your site to learn what they think needs to be done, why, and what the expected outcome should be. You'll probably have to pay for this. You will probably have to give them read-only access to your site on Search Console. (At this stage, don't grant them write access.) Your prospective SEO should be able to give you realistic estimates of improvement, and an estimate of the work involved. If they guarantee you that their changes will give you first place in search results, find someone else.