are you having trouble CUTTING the strip or folding it? This is not the quick modern way but I find it the most accurate.
To cut it -
1. find the 45 degree line on your cutting board .....
2. lay your fabric open on your cutting board and
3. using a yard stick mark a line to cut on.
4. Cut the strip as wide as you need
Repeat for however strips you need to get the length you need.
For folding:
1. fold the strips in 1/2 raw edges together and press
2. Open the strip fold raw edges to the center and press.