Beginner Plastic Part Design (Draft)

Hi , I am fairly new to design for injection molding. I was never taught any 3D CAD at my school and just learned on my own. I wanted to hear from experienced users what their workflow is like when designing plastic parts. I have found that it is critical to have draft in your design but at the same time have had a really tough time designing with it. Simple parts (say a rectangular plastic box with features, ribs, etc) that were easy to deal with become complex if extruding with draft. For me its hard do dimension things when there are no orthogonal surfaces and everything is at an angle? Is it common practice to choose "draft" in the extruded boss/base or extruded cut windows? Or is it best to just model your part and add draft at the end? I am full of questions about the plastic part design process but dont want to overwhelm users so the draft questions will suffice for now.

thank you

SolidworksPlastics And Mold Design