Raglan sleeves are not as tricky as set- in sleeves by they are tricky. They’re tricky because they’re one of those silhouettes that will never have a ‘perfect’ fit. Just like dolman sleeves, draglines will always be present, even if it’s slight. It’s the nature of the silhouette. Just accept it.
That doesn’t mean that raglan sleeves can’t have a ‘good’ fit. The most common fit issue with raglan sleeves is that there is too much fabric at the front arm. On most women, the chest dips slightly halfway between the neck and armhole and a slight curve must be built into the pattern in order for the fabric to lay smoothly. The pattern correction is simple. Since everyone’s body is different, I highly suggest sewing a fit sample and pinning out excess to determine how and where to eliminate. Depending on your body’s shape, you may have to eliminate higher or lower or more or less than the “recommended” amount (according to textbooks). Regardless of your body’s shape though, both the front and front sleeve need to be SCOOPED at the front sleeve seam. As shown on sketch, blend to 0” at neck and undersleeve. Simple.