The first way to practice is to take a scrap material you have, and squeegee it directly on a window. You can do it either vertical or horizontal. And then take the second piece of material on to the first one.
So now, you can start your practice. But before cutting anything, there are two factors you have to think about now: the thickness of the film, and the temperature of the workspace (or the wrapped film).
The reason why you have to think about the thickness of the film is that it determines how hard you have to press the blade: the thicker the film, the harder you have to press your blade, while the thinner, the lighter you should press. Thus it depends on the film itself.
In regards to temperature, the blade the film is, the easier it is for you to judge the right depth of the blade. The harder the film is, there is the higher chance of cutting too deep. So make sure you keep the film under 25 Celsius or 75 degrees.
Last but not least, it is essential to click the blade before you cut directly on the surface, because the sharper the edge is, the more consistent your blade will be for every time. You can draw a line side to side then. That is where you would begin your cutting. It is also helpful for you to pull off the top layer at the very end.
Remember to keep the angle of the blade at a 10-degree-angle during cutting the entire time, as it will keep the blade cutting just at the right depth.
However, make sure you press hard enough. Because otherwise the top layer will not be cut deep enough. And then it will not split as a result. Even worse, it will possibly tear when you go back and pick the panel back up. So remember to press just hard enough while cutting, just to let the depth of the blade cut only to the top layer without getting too deep. It should then get pulled off cleanly without tearing.
There is something you should avoid during your practice here, which is called peaking, meaning cutting at a 45-degree-angle. It makes it very difficult to control the depth of the blade when you do your cutting. Since the blade is very sharp, this can cut through too deep.
During your practice, one thing you might want to do is to mark how many times you cut and how you did it, so you will know which one was good which one was bad.
These are examples for a straight edge cut. But there are times when you have to cut around doors or lights or bumpers. So here we also have the practice for curve cut. The tricks here are to keep the angle of the blade at 10 degrees and the pressure the same every time. Also, make sure your knife is perpendicular to the surface during the whole time, even on the curves, because it is essential, it can affect your finish otherwise. As this will help ensure that the material gets cut deep enough but also not too deep, so the bottom layer gets cut.
Here we have an example of an incorrect cut for you – just so that you can bear in mind: The blade is at a 10-degree-angle, and the pressure is fine, but as the blade goes around the corner, it dips towards the side instead of staying perpendicular.
It shortens the blade depth in this case. So it only scores the top layer instead of cutting correctly. As a result, when the top layer is removed, it will tend to tear the wrap film, which will lead to lower quality and costly re-install.
But the practice is not just about practice here, you will be able to learn from your experience, and that is the critical point.
When you finish your practice, and as the top layer is removed, there are ways to indicate how well you did here. The first step you can do is to look for any lines on the base layer there, where the cut was made. If you see any, it is an excellent indication that your blade depth went too deep.
There is also another way you can judge, which is pulled out the base layer. It will immediately show you one cut was too deep if the film gets pulled apart – because the surface energy of the window is pretty high. And it will tell which cut was not quite deep as well.