Bad results when folding and materials advice

[zzattack]

Bonjour! That's all French I know so I will continue in English

I very much like making SNES game boxes from this site, but my results are not so good yet. I see boxes from Spiral and other members and they look amazing, so I want to learn this!

First I will show you my problems:


On the left box, the cartboard is completely torn. Of course I scored it first with the blunt knife on top of the boxes. The right side is a little better, but the ink still breaks as you can see in the picture below.



When I only use very heavy photo paper, the ink does not break. But then the box feels very weak, and the flaps look wavy instead of getting nice flat 90° corners. So I think it's better to use cardboard backing. Probably the best combination is light weight glossy photo paper, pasted onto thing cardboard. Can you guys recommend paper weight and cardboard thickness?

I've tried epson semigloss (250g/m2) and HP glossy photo paper plus (300g/m2). I think semigloss looks better, but in combination with cardboard the weight is too much. Any tips for these materials?