Sometimes I find it easier to figure out the personality and feel of a character before naming them, cos it can be the key to the underlying concept- and helps narrow down what they're likely to call themselves... depending on the tone of the campaign.
Is he a Columbo-style slovenly magical detective, with pockets full of useful stuff that he unhurriedly rummages through in the midst of battle? (Just a nice colourful surname would do, or one that loosely alludes to his powers, eg. Packer, Speck, Crumb, Gulliver)
Is he an obsessively meticulous maths obessive also capable of super-accurate estimates of size and weight, who imposes his re-calculations on reality? (The Reckoner, Fraction, Determinator)
Are his powers due to being a descendent of a trickster god, and he honours his ancestor by quietly stealing a little of what he shrinks, so it never quite fits again? (pick a Trickster figure: Kid Coyote, Puck, Reynard)
Is she a small, quiet, shy small town girl whose powers developed from a latent wish-fulfillment ability after she moved into a cramped big city apartment? (Smallsville, Speck, Pint-Size, Bitsy, Lilliput)
Ned