She has to pick the HEAVIEST tool from her toolbelt.
(Note: I mean the tool that WOULD be the heaviest on Earth. In her present situation, in free fall in space, nothing weighs anything.)
Once she has carefully made her selection, she must THROW the tool away, as hard as she can throw it, in the direction OPPOSITE to where her ship is.
Newton's 3rd Law of Motion: "For every action, there is an equal and opposite REaction." When she uses a FORCE to throw the tool AWAY from the ship, there's an equal force on HER, pushing her TOWARD the ship.
Another way to look at it: The Law of Conservation of Momentum. "The total momentum of any system never changes. Whatever happens to parts of the system, their total momentum is the same as it was before the event." Look at the system of [the astronaut + the tools in her belt]. Inside the system, their total momentum is zero. If she takes a tool and throws it to the left, then the tool has some momentum pointing to the left. In order for the total momentum to remain zero, the rest of the system ... the astronaut ... must get some momentum to the right ... exactly what she needs at the moment !
No amount of twisting, jumping, bending, waving, kicking, dancing, or spinning will help her. There's NOTHING she can do with her whole self, or with any part of herself, that can make her move toward the ship. She MUST propel some mass AWAY from herself.
