Ivi, you might also look at some of your favorite toys, build them and then try and understand how the shapes fit together, or the reason one designer did what they did to get the final design. break out the scratch paper and start thinking in terms of 3d design and how your vision could be adapted. start with the basics. see if you can get your hands on a copy of Matt Hawkin's "Urban Paper" as there are some great tutorials in there. have fun, experiment and ask lots of questions!
Welcome to NPT, My first papertoy (Crush) I needed to simplify the original sketch to just plain shapes that will be easy to create, As you get more experienced you can experiment with more complex designs, then just cut out the shapes and start folding! I cut out each side as an individual shape to start with and stuck them together with sticky tape, I found it helped to understand how differant parts fit together, either that or you can use computer software to redraw your designs (I use Blender for 3d shapes-free, Pepakura to unfold them, and Gimp to illustrate them) there are some topics in the forums that should help with different programs, and different ways of design! Hope this helped a little, & good luck!