Before measuring please read the following
1. Ensure you're using a proper tailors measuring tape, a construction measuring tape is likey going to give you inaccuracies
2. Ensure you're measuring the correct parts of your body, please see the above model, or the below video walkthrough from the slø team explaining the process.
3. Measure each area twice to ensure accuracy, this whole process takes less than 1 minute, it will truly be worth it in the end!
You'll be measuring your waist, hips, and inseam
If you're stuck, google is your friend!