What is the simplest way to increase volume of mesh? This hand looks too skinny. What is the simplest way to make it fatter, especially the fingers?
In Edit Mode, you can use the Shrink/Fatten tool. &#9095; AltS
It is limited to the selection.





You can also add a displacement modifier and change the strength value.
For more control assign a vertex group to it. Create a the group and go into weight paint mode &#9096; Ctrl&#8633; Tab to paint the weights.


It seems the gif progress bar got messed up. Sorry.