Learn the six step process that covers data capture, reporting, analysis for your mobile initiatives, and understand how to monetize cross-device behavior.

Source: www.kaushik.net

This post from Avinash Kaushik, Digital Marketing Evangelist at Google, is a very good explanation on how to approach  mobile application and mobile website separately in 6 steps:

Step 1: Tag every shared link with campaign tracking parameters.

Step 2. Tag your mobile website. GTM FTW!

Step 3. Dive into Mobile Reporting and Analysis.

Step 4. Dive into Mobile Reporting and Analysis.

Step 5. Implement Cross-Device Tracking.

Step 32. Media-Mix Modeling/Experimentation.