The other day I was going through Asos for yet another time, looking for goodies to buy. While searching the maxi dresses/skirts category, I found this beautiful maxi skirt with a thigh high slit and immediately fell in love. I was about to hit the 'place order' button, when I realised I have a similar black maxi skirt sitting on the back of my closet, which I've worn maybe 2 times. So instead, I decided to try and make the slit myself, and if it failed, I would either be too pissed and sworn myself to never wear this type of skirts again, or I'd give up and buy the one that started it all.
Long story (trying to make it short), all you're going to need are a pair of scissors, a white pencil (or anything that can draw on the fabric for that matter), a big ruler, and the said skirt that you want to recreate. I used one from the basics collection at H&M; however, this and this can work too.
Draw a straight line on the place you want to cut. It doesn't really matter whether you're going to make the slit on the side or the front; I made it on the side, about 3 cm away from the side seam. Keep the fabric stable and stretched at all times, and start cutting, following the line you've drawn. Keeping the fabric stretched is very important, because otherwise the cut will turn out uneven on each side. It should look pretty neat as long as you cut slowly and have nice sharp scissors. You might also use a straight edge to keep your cut looking as professional and straight as possible.
If you're daring enough, you can make another slit on the opposite side of the skirt. Now would that look good.
Now if you're too bored to bother making one skirt yourself, you can find some pretty cool thigh high slit skirts from Asos here, Nastygal here, or even one available at Topshop here.
See also these suggestions below:
Let me know if you need any help with it!