Effective theories provide an optimal framework to perform calculations in which separate scales are relevant. When applied to particle physics, effective field theory allows us to evaluate, in a systematic and very efficient way, the phenomenological implications of heavy particles at energies well below their mass. We will discuss the main ideas behind effective field theories, how they can be used in physics beyond the Standard Model in a very efficient way, and explore in detail the tecniques required to compute the renormalization group equations and the finite matching up to the one-loop order. The emphasis will be on practical details and specific calculations and tecniques, rather than a comprehensive discussion of all aspects of effective field theories. The ideas can nevertheless be used in many other theories and fields.