Help with modeling on CWRP models

[Puppetier]

So I've gotten down retexturing models fairly easy, but I'm having trouble either adding pieces to or taking them off the models (I.E. A shoulder pauldron here, or adding a skirt there etc). Does there happen to be a tutorial that someone has made somewhere for this? I'm mildly familiar with blender to so if its a process in that then I shouldn't have to much of an issue following the instructions on that. I just want to be able to make actually custom models instead of simple reskins. Any help is appreciated :D

My goal is to be able to turn something like this [IMG]https://steamuserimages-a.akamaihd.net/ugc/170416213803295723/44D404DAB05BCEEECC9FF4DEC5E050B84CA7253D/[/IMG]

Into something like this [IMG]https://steamuserimages-a.akamaihd.net/ugc/170416213803294036/4A3B572D4F6E4DDE9C969B7736F0A4CAF2B4FA0C/[/IMG]