Advertising is very expensive but usually it is what people will try first. Advertisements in local magazines and papers can cost hundreds of pounds with no guarantee of success. Trade fairs are another way of getting yourself known but again, the return in investment has to be considered as participation can be costly.
Most people who start in business have a website, but few think about search engine optimisation (SEO) as a way of driving business to their door. SEO is considered some sort of dark art which people do not understand. It isn't but it takes time to learn and it is not something you do once and then forget about. You have to work at it every month and that is why SEO companies offer a monthly package. Then you can forget about it.
How effective is SEO? Well, if done right, it is very effective at driving traffic to your business. Over 90% of people research online before purchasing a product or service. If you are not showing up near the top of the search you will get missed. And in fact, the top 3 places are the most coveted as they get the most clicks.
You can do SEO yourself of course which would make it free but most people don't have the time to do it properly. If you want to drive business to your website then investing in SEO makes financial sense.