OP: Spend the long winter nights learning all about it yourself with the help of
Fresh Bananas.
Nodding in agreement - if you know enough to do the job well, you'll know enough to speak with prospective service providers and separate the wheat from the chaff. You may not have time to actually do the job, and run your company, but you will be able to take on some of the activities needing done, thus controlling your costs.
If you know what needs done and an SEO agency/consultant knows what needs done, and you're able to do many of the tasks they can do anyway, it frees them up to do the online marketing things you aren't as skilled at (technical, ppc landing pages, conversion rate optimisation, etc).
Since many of them are the ones paying for some apps/tools, or have developed their own, you should be asking what they've got and how can it help you. Competitive or comparative backlink reports can be done in seconds on some systems, which manually would take ages. The same is true for keyword research, including finding what keywords your competition ranks for and how much traffic they likely get as a result.
Finding duplicate content within the site, or amongst external sites - that's easy with the right tools. But if you're suffering from a penalty or loss of rankings, figuring out what caused it and how to fix it is something that make or break a company financially. Do you want to wait 3 to 6 months to find out your theory was wrong and you've got to now come up with a new one, and wait another 6 months?
Get them on point doing things like segmenting your visitors to identify the common traits amongst buyers. You may find that limiting PPC to rural areas will double your profits, or that those short tail keywords you want as trophies are terrible a paying the bills - so you can refocus on the long tail.
Finding the pages that have high exit rates/bounce rates, the devices that do great or poorly - the analysis and plan as a result is something you won't get overnight, no matter how good the Fresh Bananas training program.
If you're hiring a consultant, then let them navigate while you pedal, fast. If you're hiring a service provider, then share the work load.
Remember, a lack of experience means that someone is experimenting on your site, with you footing the bill and taking all the risk. Might as well roll the dice yourself if you are feeling lucky. Or, get someone who's been there and done that enough times to do it in their sleep, pay the extra overhead for reduced risks, and hope for the best.