Self-trimming disaster-May I please have some clarification on Feye's U-shape method?

[Charlotte:)]

I just tried Feye's method of self-trimming in the u-shape:
http://forums.longhaircommunity.com/vbjournal.php?do=article&articleid=199

My hemline isn't a u-shape at all; it's just jagged and uneven. I don't think I understand all the directions very well (even after watching Habioku's video on Youtube). First of all, do I still have to part my hair in the middle if I always wear it to the side? Second of all, what exactly is she doing in step 4? Is she just repeating step 2? I also have no idea what step 5 is all about, but since it's not recommended, I'm not sure I want to bother with it at all, since I'm already having so much trouble. I have already lost 3 inches of hair trying to fix my hemline :(

[Joliebaby]

Steps 4 and 5 are repeats for "perfectionists", so you can do the steps again to catch any slight unevenness, but they are not necessary.

I'm not sure about the parting thing - If you always wear a side part, I'd just wear the same part when trimming, I think??

[Artsy]

I wear a side part? but I did the self trim with the middle part. Otherwise everything will be uneven and shifted to the side. The key I think is to have a straight middle part at the back of your head to centre your u or v.