I cannot stand crooked chevon print...it irks me! Follow these steps and it will be perfectly straight and even!
First, draw a grid on your canvas or whatever you want to paint. I used a tape measure to mark the spaces and then used painters tape to draw my lines. It works better than a ruler because it's stuck to the page and wont move. You'll see below how big each chevron line is, so you may have to adjust how many rows and columns you make depending on how big you want them:
Next, take a small piece of tape, and draw a line from corner to corner on each square:
Last, erase the horizontal and vertical lines you made in the grid in the beginning:
Now you have perfect chevron!