No need at all to apologize!
What you describe will help you determine how your site is currently performing, but may or may not help you determine the best keywords to target.
If you're just interested in learning how you currently rank for some keywords, you can utilize the Keyword Explorer, search by "root domain," enter your domain, and see how you're doing. Another approach, like you mentioned, is to add keywords within your campaign and begin tracking for them. Again, this will really only show you how your site is currently performing.
A really simple approach to determining the best keywords to target is what most people refer to as keyword research:
- Think through what it is that you do: look at your website pages, products, services, assets, etc and try to determine the best keywords, key phrases, and topics to target.
- Use Moz's Keyword Explorer, or a similar tool, to identify the keywords and key phrases with the most potential.
- A simple approach is to jot down a handful of words or phrases you think your audience might use to search for the given piece of content. Then, run each through Moz's keyword explorer, and do your best to find the words and phrases with high search volume, low difficulty, and highest organic CTR. Or utilize the "Priority" metric which more or less sums the others up.
In regards to your location, you may not be able to find super-accurate search data for your specific town or city, but you should be able to get a feel for searcher behavior by looking at the global numbers. You can use tools like Google Trends to hone in on your state and region if you'd like.
Moz has a "Beginner's Guide to SEO" that I would recommend. Though slightly outdated and currently being rewritten, there's a chapter on keyword research that has some great insight: https://moz.com/beginners-guide-to-seo/keyword-research
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