Stating things positively draws the reader's attention. Watch for the word not and try to restate the idea more effectively.
Negative: She often did not eat on time.
Positive: She often ate late.
Try to replace a word or phrase plus not with its antonym. See the following examples:
Negative: was not present
Positive: absent
Negative: did not remember
Positive: forgot
Reserve the negative form for those cases where it produces the desired effect:
"Of all noises, I think music is the least disagreeable." - Samuel Johnson