All you need to do is to select a responsive theme and the theme will automatically adjust the site to fit the device that is displaying the site.
It is as simple as that.

Well, I sell mobile websites pretty successfuk and easy. Before I started and lokking into the market, around 2 years ago, I noticed that it will become a hughe thing. And today it is. I have a restaurant client whom I consult since 10 years and his destop website receives around 800 visits a month. 2 weeks ago I looked up the google analytics stats again and you know what, it showed me that already over 400 searches came from a mobile device, Wow. By site I sell mobile websites for 400 € and a monthly technical fee of 12 €. This works brilliant.

Back to your question. I tried to create my own mobile site builder software, but noticed while talking to all the coder, that it will become difficult, special in terms of upgrades to new mobile technologies and devices. Therefor I decided to look at a very strong existing solution, which is not expensive and moneywise strong enough to stay on the market. I found one. And I am very happy with it.

And if clients do already have a website, I create a subdomain on their host like, m.yourcompany.com and create a redirection code to paste into their html page.
This code checks if a user searches from a mobile device like a smartphone or a desktop pc. Does the search caome from a mobile device to user recieves automatically the mobile version and the other way round.

If business owner asks me, why they need a mobile website I tell him my expierence with my restaurant client. over 50 % searches from mobile devices. And then I show him on my Samsung III mini, how his existing websites appears on the smartphone and point him to the zoomin in and out problem and to find the searched answer quick. Now he has feeling of what I am talking. After this he is already pretty more open for new infos to become better than his competiors. So I am showing him a ready mobile website from a client and show him the advantages. Godo design, one click to call, one click to special offers, one click to google maps to find him better and one click to start the navigation to his place. I also tell him that he isn't able not to work with a mobile version if he wants to stay in the market. Because if he doesn't do it, his competitior will do it and he will loose clients.

So 400 € one time fee and 12 € a month means nothing to be one of the early birds in his niche.

My quote is 2 presentations for one order.

I also created a flyer to hand out to his clients to ask them to add a comment on golocal and yelp.
The print file is for free, if it is not personalized with logo and adress. Most of them wants it personalized and I charge 30 € for it in addition. And they want me to print it and I make additional 20 € for 1000 flyers, ordering at an onlineprinter. Easy doing. This flyer shows him my design quality and my marketing knowledge. And very often it end in a markeing consultant job, too.

This are my expierences. If you have any further questions I am glad to answer them.

Thumbs up.