Here are 3 simple things you can ask when you are having your site built:

1. Is Structural HyperText Markup Language (HTML) being used correctly?

It is really that simple – using html as it was intended, as structural
markup, keeping the presentation separate from the content. The HTML code
should be structured according to web standards, using the proper <h1>,
<h2> tags and wrapping paragraph structures in <p> tags. With
proper semantic use of HTML the search engines can derive intended meaning from
the content and correctly index your page.

Even if your site looks good in the browser it does not mean your site is using
valid HTML code. While the browsers can still read non-compliant code, the
search engine spiders have trouble with it. It all sounds so simple, but the sad
reality is that as long as web browsers continue to accept invalid code it will
always be a problem. That leaves it up to you to make sure that your site is as
close to standards as possible.

2. Does your site use Cascading Style Sheets (CSS)

I know this was said before, but it is so important, keep the
presentation separate from the structure, design separate from the data, the
layout separate from the content. CSS controls the way your site looks and it
is in a separate file so when the search engine spiders come to your site they
get the meat not all the stuff that decorates the plate.

3. Check your site in a validating tool

Whether your website code is currently 100% compliant, or a few rules were
broken in order to accommodate old browsers, it’s always good to know if your
site is compliant. There is a great and free validation tool at the World Wide Web Consortium site that can validate your html code as well as your
CSS.

There are also many other benefits besides SEO to using web standards:

Easier to read the code – Since the design is separated from the
structure it is much easier to hand the code off to other designers or
developers for site maintenance.

Valid code saves time finding
bugs – A validation tool
takes a web page and validates the code against the web standards recommended
by the W3C. So instead of spending many frustrating hours trying to fix a
problem in one browser a validation tool will quite often find the problem for
you.

Content is separate from the
style - This makes it
easier to create different style sheets for alternative browsers and devices,
broadening your audience.

Web standards are forward compatible – When sites are designed using web
standards it is more likely your site will continue to look as good as it
should as newer browsers are released.

The money you spend in making sure your site is web standard compliant will save
you money in pay per click costs as well as site maintenance. While there are
many things to consider in marketing your site, this is one of the easiest and
most important steps you can take to increase the success of your site over the
long term.

Further reading: Programming Matters for Search Engine Optimization, The Dollars and Sense of Building to Standards