Getting the Wider View ...
Many small or 'one-man' businesses rely on word of mouth recommendation rather than advertising - and that often works very well in the local area. However, having some kind of presence on the internet opens up further opportunities.  Besides, a good website will capitalise on your good reputation. You could reach further afield; the internet can be a cost effective way of making your mark - setting out your stall in what is potentially a worldwide marketplace.

Responsive websites, mobilization ... simply put web sites should work neatly on any size screen, whether on a desktop PC, laptop, or mobile device. Older websites can even be converted to function (and look good) on mobile devices too.

Do I Really Need a Website?

If you are considering using a website to promote your business for the first time you might want to test the water first, for a modest outlay.  A simple website could be the right choice for you.  At the very least, your services and products will be there to be found.
Accessing the internet using a mobile phone is the most common means for potential customers who are searching for the very services you offer.