[4webmaster]

Here is a great strategy.
I hate offline because I want to expand mobile website sales.
So you have different choices like FB ads, Google Ads, Classified ads.
Now you must target the right niche of course.

PPC... is great but they always land on my main web design site for mobile, they look at my pages, portfolio, mobile stats, videos, very pro site... I even offer a free guide in exchange of their email but for less than 3 min, they exit without leaving a single email.

Conclusion: They have all they need to know about mobile on my mobile website design company, they are no more "curious".

The problem
1- You lose prospects email
2- You lose advertising money

Solved.

Getting a nice very niched theme landing page with just simple info with a opt-in form have a huge conversion rate.

I don't want to give them a mobile marketing guide (no curiosity) or other freebies for opt-in but let them know that they will have access to the live demo of a mobile site they can have.
When they enter their email (autoresponder) from my landing page they are redirect to a mobile device simulator where they can play with the mobile website (I think you have to touch to believe) and when they finished they have access to main site.

1- I have their email
2- They are happy with the demo and place an order.

[networkempire]

Great post. Yes, it's a good idea to give access to a simulator and get leads.

[Appopolis]

Use split testing and determine the ROI of all methods within a time frame. Re-test. Conclude.