If you are looking to have a website designed then you will want to find a decent web designer who you can rely upon. Firstly you need to consider if you want to use a local company or individual or if you are would rather use a company that is some distance away. Often people chose companies that are not within their local area as they may be cheaper or it may be that they are a larger organisation and better suited to your project.
If you do choose to use a designer from another country, they will often charge less, but you may then have the difficulty with working with someone that lives in a different time zone or may not speak very good English, making it harder to portray exactly what you want and get answers to your questions quickly.
If you are using an agency, you may want to go in and meet with the designer and programmers to discuss how you want your site to look. As often trying to portray this over the phone can be difficult. A good designer will also be able to make recommendations to you as to what they believe you should include and how it should be laid out as they will already have experience in this.