Zenobia has nailed it again! Mia has more than painting. Many times the "more than" and "less than" clues give it away. And jseven had an important clue also.
Here are some tips that I've found helpful. After you've done the positives and negatives, go through the clues that specify a "before or after" or a "more than" or "less than." If the increment is days of the week or dollars and the clue says "Mary spent 3 more dollars than Vicki," click down 3 rows (or 3 x's) from the top on Mary's column and 3 rows up (or 3 x's) from the bottom on Vicki's column.
Pay attention to those clues where the increment is 15 years or 5 points (in other words not an increment of one). For example, if each increment is 5 points and the clue says "the person who wore a red shirt scored 20 points more than the person who wore a blue shirt." you can place 4 x's (4 x 5 = 20) from the top going down on the red shirt column and 4 x's from the bottom going up the blue shirt column.
Hope these techniques help you.