I'm going to show you how to sew the most common darts - single and straight (don't read too much into that!) - using the Mathilde blouse as an example. Here we go...
Mark the dart lines - or "legs" - onto the wrong side of the fabric when cutting out the pattern (read more about marking and cutting fabric). As well as marking the legs, I also like to draw in the central line of the dart to make the next step easier...
Press the fold to neaten it.
Stitch the dart legs together, starting from the edge of the fabric moving towards the tip of the dart. It's tempting to go the other way, but if you do so there’s a good chance your thread will get all tangled up at the beginning.
You can back tack the stitching when starting from the edge, but don’t back tack the stitching at the tip or the thread will cause an unsightly lump! Instead, stitch off the edge of the fabric and cut the threads leaving enough so you can tie them together by hand into a tight double knot.
Press well! A bust dart should be pressed downwards, or if you’re working on a waistline dart press it towards the centre. If your fabric can handle it, you can use the steam in your iron to shape the point and create a nice, smoothly curved dart. A tailor’s ham - or substitute such as a rolled up towel - will help with shaping.
Et voila! Lovely, shapely darts.
Want more tips on sewing darts? Check out this post on five or six different ways of sewing darts.