The strong interactions program of NA61/SHINE, a fixed-target experiment at the CERN SPS, focuses on the search for the critical point of strongly interacting matter. The strategy of the collaboration is to perform a comprehensive two-dimensional scan of the phase diagram µB–T by changing the collision energy and the system size. If in this scenario the system freeze-out occurs in the vicinity of the possible critical point, then a region of enhanced fluctuations is expected to be seen by properly sensitive fluctuation measures. The paper reviews the possible ways to study multiplicity fluctuations, e.g. in terms of pseudorapidity dependence of strongly intensive quantities or the study of the higher-order moments of multiplicity distributions. An important issue of the results corrections and possible systematic problems in the analysis is addressed.