I have been making my own patterns for over 30 years. This tutorial is for a beginner who has never attempted pattern making.

Supplies

Measuring tape
Butcher paper or wrapping paper
Pen or pencil
Calculator,if needed

Step 1: Measuring

Begin by taking measurements of the body.
1. Shoulder to shoulder ,add 1 1/2 inches
2. Sleeve top, armhole ,add 1 1/2 inches
3. Neck to shoulder, add 1 1/2 inches
4. Wrist ,add 1 1/2 inches
5. Arm hole,add 3 inches
6. Chest , divide by 2 , add 1 1/2 inches ( for example : 40 inches divided by 2=20+1 1/2 inches = 21 1/2 inches)
7. Waist and hip : same as chest
8. Neck, divide by 2, add 1 1/2 inches
9. Neck to waist (front), add 1 1/2 inches
10. Neck to waist (back), add 1 1/2 inches
11. Leg add 4 inches
12: Thigh, add 2 inches
13 . Ankle, add 2 inches
14. Arm, add 3 inches
15: inseam , add 3 inches

Step 2: Create the Pattern

Sketch a basic shirt front onto the paper. Adjust the size of the shirt front to match your measurements.
Do this for the rest of the shirt pieces . You need to make a neck lining by using the shirt front and back to create pattern pieces that are identical to the shirt front and back neck area.. The pattern pieces will be approximately 2 inches long.

Do the same with the pants.

Now you have a basic pattern that can be adapted to whatever clothing or costume you’d like to create.