You can either render visuals directly from within your 3D apparel software or import your object into an external render software. While the first option will generally be faster and easy to use, the increase in quality you can achieve by using additional render software is huge. Software like Modo, Blender, Maya or many others offer tons of additional render options to improve the realism and quality of your visual based on the physical calculation and render engine that are applied. However, it requires additional skills to work in such software, usually done by 3D artists. While the extra value is definitely worth investing the time you might want to evaluate whether you are at a point where you want to go for ultimate quality (e.g. for presentations) or if you are still at a stage where your product is changing a lot (e.g. within design phases). Further, if you are just starting off with 3D, you might want to focus on mastering the 3D apparel software first; but taking the desired 3D render software into consideration is essential for your future planning and end-to-end workflow.
Polygondressing 