This document provides tips for guerrilla testing of mobile applications and websites. It recommends testing early and often in real-world environments with actual users rather than just in controlled lab settings. Specific tips include testing scripts, using pre-formatted response sheets, testing in crowded noisy places, getting permission from location owners, using incentives to attract testers, having multiple testers, considering testing at cafes or with a mobile testing desk, and screening potential testers to find appropriate participants. The document emphasizes the importance of testing until problems are found and using techniques like first click testing, card sorting, and tree testing to gather user feedback.