When you decrease for the raglan sleeves, you want gradual slants along the sides, right? So. . .
Knit the first two stitches together and the last two stitches together on the decrease rows.
You'll work 12 rows even, without decreasing, and then decrease as above on the next row and every 6 rows after that. So if your first decrease row is called row 1, you'll decrease on rows 7, 13, 19, 25, etc., until you have the number of stitches left that the pattern calls for.