Your choice of SA method depends on how many parameters you would like to include in the SA and on the computational time required for simulating your model (and on the time available). If you would like to carry out an uncertainty quantification, the choice of method also depends on information available on input (parameter) uncertainties. Provide a rough estimation on the above, and then I can try to suggest a method.
If your numerical forward model has been validated, then it depends on the way you run the forward model. Generally all the SA methods are available. But variance based (VB) method requires intensive evaluation of the forward model, then the meta-model is necessary to replace the forward model; while element effect (EE) method is also powerful even with limited evaluation of the forward model.
Global sensitivity analysis (Sobol' indices) is definitely the most popular method these days. In conjunction with surrogate models such as polynomial chaos expansions (PCE), this is probably the most efficient method around.
If your model has 10 input parameters, about 100-200 runs (eg, Latin Hypercube Sampling) should be sufficient to build a PCE, from which you get analytically the Sobol' sensitivity indices.