Wordpress was initially created for bloggers, not for huge corporate sites or specific needs. So straight out of the box it has many limitations. Genesis, too, is a standard framework and while it's great for 80% of people, we are among the 20% who have unmet needs.
That's where plugins come in. They add features and functionality to Wordpress. With plugins you can turn a bog-standard blog into a membership site, sell products, add tables - whatever you can think of. There's a plugin for everything.
Here are the ones you can install right away, even if you don't use them on day 1.
This will give us greater control of our logo. The one complaint I have with Genesis is that its default logo sizes are weird and bad. I recently discovered this plugin and it solves that problem. To start with, a basic text logo is fine - in fact, my most successful sites don't have actual logos.
Contact Form 7
This goes on the contact us page and lets people send emails. It's mostly idiots trying to sell SEO services but sometimes you get real people.
EasyAzon (free) and EasyAzon Pro (paid)
This is the plugin we use to actually make money. There are other options but for now this is my default. You can't actually use it until you get an Amazon account, and the Pro version costs money, so you might want to wait till you get that Amazon approval before buying.
Genesis Simple Edits
This lets you change some things like the footer without messing about with any code.
Genesis Simple Sidebars
This lets you create different sidebars for different pages. So your 'best widget for kids' page can show kid widget A and B in the sidebar of that particular page.
Some Social Share Buttons (e.g. Monarch)
I have a plugin called Monarch from when I bought the Divi themes. It adds social share buttons to various places on the site. On Britain's Smallest Shop I have them on the left:
If you click one of the icons you can quickly share that page. I can also put them at the start and end of individual articles, make them float in the corner and so on.
There are probably millions of similar plugins.
Q2W3 Fixed Widget
This one lets you make something stick in the sidebar. Normally your page is longer than your sidebar. This widget lets you make one element in the sidebar 'stick' so as you scroll down there's always something there on the sidebar - perfect for keeping an advert visible.
Scroll Back to Top
Just essential. I use this all the time when I'm building a site - jumping up and down to check various things. You can change the colours etc to match your theme.
Table of Contents Plus
This one generates a table of contents based on your headings and subheadings. There's nothing similar on Squarespace and that's the single worst thing about it.
Very useful, I'm sure you'll agree. And easy to set up. (This example has the sections automatically numbered, which I think is ugly, but there you go.)
Tablepress and Tablepress Responsive
Yet another feature sorely lacking in Squarespace, dammit. With these you can generate tables and make sure they look good on smartphones. Tables look like this:
Google LOVES structured data, so it's really worth spending the time putting a table on any page that might use one.
This is for backing up your site.
This will get a full post on its own. It makes it easy to do all the things you need to do to get noticed by Google.