The most important tool for making the perfect chevrons is hobbyist tape. This is 6mm, but it comes in many other widths. This will give you super clean lines and usually won't pull your primer off.
The first strip is by far the most important. This is where you will base all of your other lines off of, so make sure its just right. It is not uncommon to have to re-lay the strip multiple times. Take extra time to make sure you get it right.
A center mark has been placed for reference to show where the tip of the primary chevron is. A a second strip of tape has been added to add line thickness.
A second strip has been placed on the other side so that it makes a square with the other tape, highlighted in the picture above. Helpful note: if the piece you are working on is symmetrical, use reference points, such as rivets to properly place your lines.
After placing the second strip you can start to see if your lines are actually symmetrical. This will ensure that all other lines you place will also be even and symmetrical.
There was a bit of excess tape on the model. If you place your tape carefully, you will not have to worry about removing excess tape. If you do have to, make sure to cut the tape gently, so as not to score the model.
To ensure each stripe is uniformly thick, adding the appropriate amount of tiny strips of tape inbetween your taped off sections is much less risky then just eyeballing it.
This is what it looks like when all sections are taped off.
After removing the spacer tape strips, apply strips in the middle of each line so paint doesn't get through the cracks and gaps.
While not essential, it is highly recommended airbrushing your paint on for doing chevrons. the airbrush is a lot smoother, goes on thinner, and does not get paint inside the creases of tape.
Here is the Armor plate with airbrush paint applied. Make sure to wait extra time to ensure the paint is fully dry before CAREFULLY peeling away the tape.
As you can see, some of the black paint has chipped away while peeling off the tape. This usually doesn't happen, and is most likely due to improper resin washing or from priming in the cold, New England weather. Either way, it is not a problem. These exposed areas are perfect spots to make rust, or armor damage in a seemingly natural position. These can also be easily touched up with the airbrush, or by hand if you are going for a clean look.
Apply your trim paint and you are basically all set. You now know how to make crisp, clean chevrons!