It can be blessing if the web designer is aware of how important SEO is and similarly the SEO knows how important a good and attractive website is! Most of the time when hiring a company to design your website which you plan to optimize for the search engines the main problem faced is whether to include flash or not. Designers say flash is indexable and that they have read it in forums or etc which says flash sites can rank in Search engines with out a problem while the SEO guy will say that a non flash site has better and quicker chances of getting into rankings. So how do you decide on what to go for?

The main thing that you need to keep in mind while deciding upon a designer for your website is Can he design an attractive site and more importantly can he design a search engine friendly site?
When selecting a designer take a look at the portfolio of the company. Take a look at the previous work done by the company, see whether they can build you an effective site which targets your target audience. If they are experienced then they must have done research about the colors that make people act in a different way, or the various eye tracking studies highlight the various colors that have people respond differently. The other issues like where to place the logo to highlight it the way that it has maximum effect on the visitors plus make the design looks natural rather all decked up but unattractive.

The best place where you can find such combination in designers is generally a company where it provides both website designing as well as SEO services as the people working there are more thorough about the aspects of both the fields since the company deals in both and professionally are a better bet.