Instrumentation is crucial in Runtime Verification because it should ensure that monitors are fed with relevant and accurate information about the executing program under monitoring. While expressive instrumentation is desirable to handle any possible monitoring scenario, instrumentation should also efficiently capture the just-needed information and impact the monitoring program as least as possible. This tutorial comprehensively overviews the instrumentation process and considerations for single and multithreaded programs. We discuss often overlooked aspects in instrumenting multithreaded programs. We also cover metrics for evaluating the efficiency and effectiveness of instrumentation. We use four hands-on use cases to apply the introduced concepts and provide practical guidance on choosing and applying instrumentation for runtime verification.