Eclipse Users
If you are developing in Eclipse/ADT (and have set up Keytool and Jarsigner as described above in Basic Setup for Signing), signing in debug mode is enabled by default. When you run or debug your application, ADT signs the .apk with the debug certificate, runs zipalign on the package, then installs it on the selected emulator or connected device. No specific action on your part is needed, provided ADT has access to Keytool.