It's easy to get buried in ideas on SEO, but start with the basics...
- Validate your code
- Have a descriptive <title>
- Have a meta "description" tag that contains one or two key sentences about the company
- Have a sitemap and register with Google
The layout is very intuitive, and it's instantly obvious what the site is about. I also like how you list everything you do right there on the front page. And the color scheme is certainly practical. People who need to visit your site aren't there to be entertained or look at pretty pictures, so you aren't wasting their time.
My only suggestions:
- I see buttons that refer to a shopping cart (at the lower right of the header). But there's no button leading to the shop itself. I'd add one.
- the links in the left-hand navigation panel change color when you mouse over them, indicating that they 'do' something. I'd recommend doing something similar to the horizontal links under the banner.
- about those links - are they highlighting topics of particular interest? Certainly a good idea, but if so I'd definitely do something to make them stand out a little.
- I took a look at the water softener page, and I see the list of softener types along with images of them. Maybe under the headers for each item, you could put a short description of each type. I assume that where you would use a simplex water softener, there's some particular reason you're using that instead of a duplex or a bespoke. The description could say something about that.