If your bust is larger than a B cup, you might want to move the bust dart down a little as part of your bust adjustment. This T-shirt pattern has a bust dart, which I like for helping with fit, but after I made the top once, I decided I would move the dart down a little. This method is based on a tip in Sandra Betzina's Power Sewing book.
First, I drew a line (in green) that represents the foldline of the dart. Next, I drew a "box" around my dart. Then, I drew two, parallel lines that are perpendicular to the grainline. The top line intersects with the dart foldline. The bottom line is the point to which I'm going to move the dart. You'll see in a second.
I cut out the "box" around the dart. The tip, or apex, of the dart has been moved down to the lower line.
I keep a lot of larger scraps of pattern paper on hand for things like this. Can you see the gap along the side seam line, between the lower point of the armhole and the top of the dart? Now I need to draw in a new line and blend it in. I use a design curve for this, or else get out the original pattern tissue and some carbon paper and trace over the style lines printed on the pattern tissue.
Now it's time to true up the dart. Fold your dart along the foldline you drew in, and make sure the dart legs are matching up to each other. Fold it down (after all, that is how we press our darts in our garments). You'll have a little pucker in the paper. Use some tape or a pin to hold it there.