I understand completely. It is very tricky and at times frustrating when learning a new technique/skill.
Checked out the video and I don't think you should be so hard on yourself. We all started somewhere and I am sure even though we don't always show them (we're not all as brave as you), everyone has a pretty rough first go.
In regards to scoring, I am guessing by looking at it that you used an exacto knife to score. If you are struggling with it, I honestly think a sharp pen (I use a 0.5 size pen). If the knife way comes easily to you it can be a little bit better, but I just find the pens work a lot nicer because you can use a straightedge more easily with pens.
In regards to the warping, I can see that a lot of it has to do with your gluing process. Warping usually happens when you have something off alignment at point A and it causes a ripple effect to throw off and warp point B later on. Essentially, if the top of the helmet is not well aligned, it can cause the middle or bottom to warp as they try and accommodate that misaligned spot which gets worse the further away from it you get. When gluing pep pieces together, you need to ensure the numbers line up before the glue dries. When lining them up, you go from the outer edge of the number set... say for 107, you would go from the leftmost "hat" on the 1 to the rightmost elbow on the 7, thinking of it as a box like that with it lined up with the numbers on the other piece. The numbers are alignment points to make sure the pieces are properly placed. If you can get them down right it will greatly reduce the warping. However there may be some still from the thickness of the cardstock throwing it off also. In general though, if the warping isn't too bad, you can force it out by continuing to build, as future pieces can hold the warped parts in place a bit better.
I think much of the talk of popsicle sticks and stuff was assuming you were already finished with the piece as they can be used to hold the piece in the correct position.
I suggest probably starting over and making sure it lines up well. It can be helpful to practice on low-def versions of helmets as they will have bigger pieces and build in less time so you can get some experience finishing a piece that is a bit easier to work with, the details on HD and MD pieces can really make it hard to align! Keep up the good work though, I promise you are doing a lot better than I did my first time with pepakura, so don't be so hard on yourself! I know it can be frustrating but that's learning, you struggle a bit at first but as you get experience with the skills needed it becomes easier and easier.
Also, I know someone else will anyways, so I'll throw in the obligatory "If you are struggling too much with pep, try foam". It IS easier to work with, but I do think a well trained pepakura build can get some amazing results, foam is great for quickly making mid-level armor, but there needs to be an artistic background to really get the most out of foam. Pep and Bondo is a bit more of an industrial skill which has a harder initial skill, but quickly becomes easier to work with as you get more comfortable with it.
Checked out the video and I don't think you should be so hard on yourself. We all started somewhere and I am sure even though we don't always show them (we're not all as brave as you), everyone has a pretty rough first go.
In regards to scoring, I am guessing by looking at it that you used an exacto knife to score. If you are struggling with it, I honestly think a sharp pen (I use a 0.5 size pen). If the knife way comes easily to you it can be a little bit better, but I just find the pens work a lot nicer because you can use a straightedge more easily with pens.
In regards to the warping, I can see that a lot of it has to do with your gluing process. Warping usually happens when you have something off alignment at point A and it causes a ripple effect to throw off and warp point B later on. Essentially, if the top of the helmet is not well aligned, it can cause the middle or bottom to warp as they try and accommodate that misaligned spot which gets worse the further away from it you get. When gluing pep pieces together, you need to ensure the numbers line up before the glue dries. When lining them up, you go from the outer edge of the number set... say for 107, you would go from the leftmost "hat" on the 1 to the rightmost elbow on the 7, thinking of it as a box like that with it lined up with the numbers on the other piece. The numbers are alignment points to make sure the pieces are properly placed. If you can get them down right it will greatly reduce the warping. However there may be some still from the thickness of the cardstock throwing it off also. In general though, if the warping isn't too bad, you can force it out by continuing to build, as future pieces can hold the warped parts in place a bit better.
I think much of the talk of popsicle sticks and stuff was assuming you were already finished with the piece as they can be used to hold the piece in the correct position.
I suggest probably starting over and making sure it lines up well. It can be helpful to practice on low-def versions of helmets as they will have bigger pieces and build in less time so you can get some experience finishing a piece that is a bit easier to work with, the details on HD and MD pieces can really make it hard to align! Keep up the good work though, I promise you are doing a lot better than I did my first time with pepakura, so don't be so hard on yourself! I know it can be frustrating but that's learning, you struggle a bit at first but as you get experience with the skills needed it becomes easier and easier.
Also, I know someone else will anyways, so I'll throw in the obligatory "If you are struggling too much with pep, try foam". It IS easier to work with, but I do think a well trained pepakura build can get some amazing results, foam is great for quickly making mid-level armor, but there needs to be an artistic background to really get the most out of foam. Pep and Bondo is a bit more of an industrial skill which has a harder initial skill, but quickly becomes easier to work with as you get more comfortable with it.
