Values for Parameters

Hi all,
I just wonder if there is a recipe to pick “the most correct values” for parameters. In other words, which criteria should we consider when parameterizing the model?. I constructed a model, which is a blend of three models, and I don’t how to assign good values for the parameters.
Best regards,

Either choose the parameters based on micro studies (usually called calibration) or estimate them, either formally or loosely by matching some moments.