I always have a number of considerations when going about picking a web design company.
I need to know the total cost of the project. We all have different budgets, however there are some very good deals to get, if you are willing to search around.
I am not a web designer myself; I actually help people with their Medical negligence claims and I also work for a firm who offer a upvc front door service. I do however have a large amount of sites on the net.
When choosing a company it is important to look at their portfolio, this will give you a good insight into the type of work they do.
Most web desgn firms will offer additional services such as optimisation, a web promotion service and may also submit your website to the search engines.
For me the website they have created for you should be fully optimised anyway and I would also expect the web design firm should submit the site to the search engines as a matter of course. It is always worth asking to make sure.
I always ask for the person or company to add a link from their site to mine as this is likely to increase my overall search engine position as well as the websites page rank. The higher the page rank, the more visitors you are likely to obtain.
I also like the google adwords program. This is where you pay per click to your website and your advert is likely to appear in the first or second page of the results, on the right hand side.
You can also write articles, like the one I am here or you could pay for a manual article submission service to do it for you. This will potentially obtain you even more additional links and visitors.