I also can't do the one with the RED and GREEN circles thing. Please, help, it's just very hard.
With this, I spent ages getting all the green ones two to a circle, putting them on the outside edge, then trying to join them together in the middle... before realising if i just concentrated on getting two RED ones on the outside edge of each circle it was rediculously easy and ive wasted about 20 minutes being an idiot. bwhahaha.
Hope that helps...
edit: not to insinuate that anyone who cant do this puzzle is an idiot in the slightest. I just inadvertently found an easy method and ignored it for ages because i was too busy trying something that didnt work.