Like replicand's 3rd suggestion, it adds a fair amount of polys, but what I do is grab the outer line of edges, extrude the edges a a small amount - and you have to use a little care in corners because sometimes this leaves you with crossed polys, which you should fix at this point - and then select the outer loops of new polygons and bevel those.  It's not as bad as it sounds because you can do the these operations all at once.

A big caveat of this technique is, try really hard to get the base geometry of the clothing item as close to its final state as you can, because once you extrude out the trims, the model because a lot harder to adjust without trashing up that nice new trim work.

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