According to the Chinese Zodiac, 2013 is the Year of the Snake. It is expected that "all things will be possible" and "saving money and being thrifty should be your top priorities." Turning that wisdom into practical action begins with an understanding of program performance and where efforts are best aimed. Get gritty with the details and eliminate that which obfuscates results.
PC, mobile and tablet should always be separate campaigns, which enables tightly themed ad groups and the ability to adjust bids accordingly. Don't opt into more than one channel because there is limited visibility into performance. An ad group might convert on PC but not on tablet, for example. Also, should you employ a single keyword ad group strategy, there is only one bid to adjust and you can get savvy with copy: “Get an insurance quote right here on your iPad!” -- which will likely convert at a higher rate.
A nested keyword construction (computers>>mobile computers>>laptops>>netbooks) allows for a more accurate comparison of desktop and mobile. The nested construction of related categories enables filtering to find more mobile-centric queries, including purchase intent. Plus, mobile queries are traditionally shorter in character length, so you can more skillfully develop corresponding ad groups.
These shorter queries are one reason you do not want to move your entire desktop campaign to mobile. Today, a smaller keyword group will suffice. If you currently employ one million keywords in your desktop account, mobile requires approximately an eighth of it.
Don't forget about voice search contributing to longer and differently phrased mobile queries. We will see more questions as keywords, so providing content to answer those questions will be key. Engines or apps also have additional data on mobile, including precise GPS and previous searches or user actions, which can disambiguate oblique phrases. Use all tools at your disposal to gain performance clarity.
It's not really news to encourage a mobile/tablet optimized site (seriously, build a mobile/tablet optimized site) but with your tablet viewers, you can probably get away without a separate site and drive visitors to your desktop page. Best practice: if you have to pick a destination site, and do not have a tablet-optimized site, choose your desktop over mobile, as size occasionally matters.
Finally, of critical importance to the mission: consumers using a mobile device are not as willing to suffer through a bad user interface. Browsing a small-screened mobile device is already fraught with peril for those on the go, so remain aware of the distinctions between mobile and a 15-inch monitor during the checkout process.
As the Zodiac counsels, to gain the greatest benefits from this year, you must control spending and use your talents wisely. Transparency is the first step to harness that which is possible (a little-known Confucius saying).