Sometimes following the same SEO strategy for targeting keywords based on their competition don't work and you may need to adopt a better strategy which gives promise of generating good inquiries by different promotional activities.
First thing your SEO process must follow is to take advantage of your physical presence of location. It must include targeted keywords which targets a local audience as you can invite them to visit your business, there would be more possibilities of getting a good conversion.
When you have more experience designing websites for a specific niche, you should select the keywords which are suitable to target audience looking for that website design company having similar websites in their portfolio. Web design for hotels, restaurant website design, Ecommerce website design are some of good example.
After gathering good clients with above two ways, now it is time to jump into competition, spend good money on SEO efforts and target competitive keywords which are hard to achieve and require more efforts.
Following above strategy would maintain the ratio of cost VS its return and you can think of promotion through search engine sequential and more effectively.