List of Materials that make life MUCH easier:
Used t-shirts that do not have side seams
self healing rotary mat the bigger the better
omnigrid ruler 6"x 24" works great
yarn ball winder
If you don't have the extra materials no biggy you can still make t-shirt yarn. The extra materials just make it faster and more accurate. As the self healing mat hat a measurement grid on it and so does the ruler so you can make all of your strips the exact same size. And it saves your hands I had so much to make that I would have gotten blisters using scissors for all of it. Ok so on to the instructions.
Lay your t-shirt out in front of you. Try to get all the wrinkles out and make it as straight as you can.
Continue cutting in one inch strips all the way across. When you are done it should look like this
Here is a close up of the top of the shirt (where you should have left 1" uncut)
Now "open" up the top where it was left uncut so that it looks like this
Now here is another important part with a pair of scissors cut diagonally from the 1st strip on the right to the 2nd strip on the left. Then the 2nd strip on the right to the 3rd strip on the left. And continue in this manner to the end. Leave the 1st strip on the left uncut for now do that at the end to avoid confusion.What this will do is give you a long strip of continuous "yarn".
This photo is the 1st cut
This photo is the second cut
Now when you are done you will have a LONG strip of 1"inch fabric