Fara McCaw, also known as FaraVR, has demonstrated a handy tutorial on how to use Blender's Lattice Modifier to refit clothes originally made for one character to another.
The advantage of this method before deforming the mesh is that it's a non-destructive workflow, meaning all changes happen on top of the original geometry, which you can still go back to, and it also allows you to work with smaller details. Obviously, it goes with the modifiers themselves to allow you to adjust parameters to your area of work.
The only downside of Lattice, unfortunately, is that it can't be mirrored due to its nature, although there are some crutches to make it work such as using Duplicate Linked.
Still, there are a number of other reasons to use a Lattice instead of simply editing the mesh, such as:
- A Lattice does not affect the texture coordinates of your mesh's surface
- The deformation made with Lattice is hard to achieve manually
- You can edit multiple objects at once with the same Lattice