do oneself down—(UK coll.) make oneself ashamed or less proud of oneself:
- Remember not to do yourself down—it is your job to sell yourself, the employer’s job to judge how well you do this.
do oneself up —(coll.) dress up for the party, etc.; make oneself more beautiful:
- After spending two hours putting makeup on and doing herself up I would hope she does look better.
Note: The expression is not equivalent in meaning to the phrase make oneself up—(of an actor preparing for the stage, etc.) apply cosmetics to one’s face:
- He started as a teenage clown, making himself up with shaving cream and lipstick.