In this paper, hearing aid fitting strategies are reviewed and candidature criteria for unilateral and bilateral fittings are discussed. Fitting strategies are primarily governed by the objectives of hearing aid fitting that can be set in different ways. Based on common goals, fitting strategies can be broken down into three stages: (1) basic fitting, (2) fine-tuning and (3) verification and validation. A fine-tuning concept basing on so-called meta-controllers is described and the issue of bilateral fitting strategies is discussed. In a first order approach, bilateral hearing aids can be fitted in parallel as unilateral aids, followed by bilateral fine-tuning, making sure that loudness is balanced and overall loudness is accepted. Parallel fitting of bilateral aids is more favourable than sequential fitting to avoid rejection because of a negative experience with unilateral amplification due to difficulties in disadvantageous listening situations. Candidature criteria are presented by means of a flow chart structuring the decision making process and arriving at the conclusion that bilateral fitting should be considered the normal case. If there is any doubt about the benefit of bilateral fitting, a trial with bilateral aids should be performed.