Optimize site for seo?

Question

Search Engine Optimization

I'm making a site for a guy from Los Angeles, he does quick car repairs after an accident. Now the prototype of the site is on my hosting https://arcane-beyond-35849.herokuapp.com/
ps: the site was designed by the man himself and the layout is shit because I redid everything five times at his request (well, you know what in such cases happens)
so I can do much better, but the question is not about that.
After that, he needs seo promotion in American Google and I asked a friend on Skype like you can take it, he says:
I don’t want to take it, in order to promote it, you need to redo a lot! (C)
I asked him what exactly, but he doesn’t answer and apparently the conversation ended there)
Now I myself became interested in what exactly is wrong for general educational purposes. Just for the future.
Here's what I thought:
1) make a picture with a broken car not on the whole screen, but at least on a third of the screen so that it does not take up useful space
2) make sure that when you click on services (for example, on towing) a new page opens, not a modal window
3) the side menu can always be shown
4) I am silent about optimizing the titles of meta tags and keywords, it's clear
. Did I miss something else?) Is there anyone who fumbles in this topic?)