Several steps are required to perfectly sew a trouser hem. To start, you have to undo the hem already present with a seam ripper (or small scissors). Then, fold your pants to the correct length by placing several pins around them to hold the fold in place! Be sure to try it on with proper footwear! Take the pants off and put them inside out. Iron the fold with an iron and measure 4 cm from the fold you just ironed. Cut the excess fabric marked with a chalk after removing the pins and put it back once the cut is finished. Make way for sewing by hand or with a machine! Take thread of the same color as the pants and use a blindstitch to sew all around 1.5 cm from the hem fold. Continue until you get to the point where you started again and then tie a knot in the thread you are about to cut. Repeat the exact same steps for the second leg!
If you don't have the soul of a seamstress, you can do it differently by buying yourself a strip of iron-on patches. It's easy, convenient, and fast! On the hardware side, you don't need much more. A pair of scissors, glass-headed needles and an iron are enough to work wonders. Cut the bottom of your garment to the desired length leaving a 4cm strip. Tuck in the hem and mark the fold with an iron! Then open the hem and lay a strip of iron-on flat on the back of the pants. Fold the hem over the veil. Take your iron again and iron the hem (watch out for the temperature!) for 25 seconds, pressing down hard. Let cool without touching! It will take you less than 5 minutes and it is very resistant!