If you're about to make your first Trousers hem, first make sure you get the measurements right! You wouldn't want to end up with one leg shorter than the other, would you?
Before hemming, it's vital to have a fitting with the Trousers and ideally with shoes. That way, you won't have any nasty surprises and the length of the Trousers will be perfect.
In the tradition, the hem is made at the heel of the shoe. So, fold the Trousers just above the heel and pin.
This pin will be your reference point for the rest of the work. To avoid the two legs having different lengths, pin the second leg at a later stage, when the Trousers are flat on the table.
Depending on your style and outfit, you may prefer your Trousers to be well above your ankles.
This is often the case these days, for both men and women.
The important thing is to always take your measurements in the right conditions and again, with the shoes you're most likely to wear with your Trousers.
To leave yourself room to change your mind or subsequently your style, make a changeable hem. That is, rather than cutting your Trousers to make your hem, you simply turn the fabric back on itself and proceed to sew.
This will allow you to unstitch your hem afterwards, if you want to add length to your Trousers!
Beware: a hem is never straight. Trousers are always longer in the back than in the front.
Your crease must therefore be curved (the difference between the front and the back must not exceed 1.5 cm).