I have sewn most of the dress on my lock machine, but you can do this also with a regular sewing machine. Matching up the thread to your bolero is advisable but not crucial. I simply do not own red serger thread and just used white, when the dress is on this does not show.
Use your favorite knit dress pattern or draw a pattern based on an existing dress or T-shirt (many tutorials on the web to help you with that). Start out with the pattern of the back piece (the one with a high neck line). Draw on your back piece a front neck line. I did it in green (just ignore the purple, I often reuse my patterns). While drawing the front neckline make sure that the shoulder is less wide, the difference should be a bit more than your sewing allowance.
On the same back piece also draw the blue line you see in the picture below. The blue line start at the shoulder end of the back piece and approximately keeping the same distance goes down and curves under the arm. The second purple line is for the red stripe I added in this version of the dress. The pattern I used is based on a pattern from Ottobre 4/2013. It is up to you if you would like a stripe in the middle or any other details you are used to include.
Now draw and cut two extra pattern pieces based on the lines you added on the back piece you started out with.
Cut your fabric (the extra shoulder pieces twice). Besides all the pieces for bias etc you will als need a long strip which will be part of the faux bolero front. My strip was about 15 cm wide and 80 cm long. The strip will have to go along side the extra pieces and the back neckline. I made sure the piece was surely long enough without actually measuring it. After cutting your pattern pieces should line up like this. Be sure that the shoulders of the main front piece are indeed less wide than the shoulders of the back piece and that the extra front pieces on the shoulders are as wide as the back piece.
I made the dress in such a way that the back of the dress has the color of the bolero until the bottom line of the red block in the front. I think this enforces the bolero feeling, but you might have different ideas about this.
Finish the front neckline and sleeves as you are used to. I put a knit bias on the neckline and a piece of double folded knit on the sleeves.
Lay down the main front piece, put the extra shoulder pieces on it in the right position (all good sides up).
Put the back piece on it with the back side of the fabric on top. The good sides of the main pieces should be facing each other (with the extra pieces in between). Sew the shoulders together. Make sure that you sew through all three layers. You will run out of front shoulder but just keep on sewing the extra front pieces to the back piece.
Now take the long strip of fabric and sew it in one motion to the extra front pieces and the back neckline. Do not start too close to the side of the strip, just leave a centimeter hanging free (this will makes the final stitching in place later easier) Start on one side and do not stretch the long strip. The first time I made this I thought that I had to stretch it like a bias, this turned out bad. If you would like to stretch something, stretch the extra front pieces, but it works fine without stretching any of the pieces.
I prefer to now put in the sleeves.
If applicable put on the extra piece in the front.
Fold the top right sides out and if necessary you can now easily cut the back and front exactly the same size to make sure the sides will match up. Then sew on the the skirt pieces. I also added some pockets to the dress in this stage.
Now fold the dress right sides out. Make sure that the seam of the bolero piece is up (just look closely to the picture then you see that the entire long strip is lying flat) this will help with the right folding.
Now align the extra front pieces to the main front piece and fold up the long strip a bit more than half (about 2/3). In my picture the long strip end of fabric now falls besides the main front piece, with your own project the piece falling besides the front might be bigger or smaller. In the beginning I mentioned not to start sewing at the beginning of the strip, that was to make this step easier. If you are satisfied with how the bolero is folded turn the dress inside out. Re-pin your side and sew them together. If you use a lock the overhanging piece will be cut of automatically (just cut it with a pair of scissors if you use a regular machine)
Finish the bottom of your dress, iron the bolero collar and you are done. If your collar keeps turning a bit and showing the seam just put a few stitches by hand on the inside.
The dress is a gift for a sligthly bigger girl but my daughter could model it.
I hope you liked it. Please let me know if anything is unclear or if you used the tutorial. I would love to hear from you.