The development of X-ray Free-Electron Lasers (XFELs) has provided unprecedentedly bright X-rays. These high intensity X-rays with ultra-short pulses provide an opportunity to explore the structure and dynamics of matter in ever more fine spatial and temporal resolutions. However, to best exploit these new machines is nontrivial: researchers need to adapt various methodologies to XFEL experiments and optimize the experimental parameters for the best data quality within a limited experimental time. In order to find the optimal methodology and parameters for any given experiment, we present a start-to-end simulation workflow that incorporates various simulation modules: including the XFEL SASE source, X-ray wave propagation, photon-matter interaction and scattering signal generation. With this thorough simulation tool, we use the example of single particle imaging of biological molecules in a variety of experimental conditions to explore the value of such simulations and draw first conclusions about an optimal experiment within the parameters explored.