To prevent other research groups from making the same errors as we did in real-world deployments of sensor networks, we share our experience from previous installations and lessons learned from them.First of all, we are finally convinced to apply the KISS principle (Keep it Simple Stupid) also to real-world deployments, especially that as researchers we tend to prefer more complex and sophisticated ideas.Second, researchers underestimate practical issues in outdoor installations, and it may lead to unexpected and time-consuming problems. For instance, we did not notice that the selected voltage regulator works reliably only in temperatures above zero degree Celsius, leading to packet losses and a long debugging process.Third, apart from extensive software tests before deployment, our protocols and applications include also self-healing instructions. They detect software bugs on run-time and restart motes if needed.With all these three major steps, we were able to run real-world sensor networks for several years without major problems, even when we do not have resources for efficient testing and debugging, the problem that most research groups have.