Sometimes it helps if you take the image of the finished piece out of your head and put it on paper!
Get some graph paper or sketch paper and start just roughly sketching in the shape of the pieces you're trying to put together. You might even cut them out like we did in the "old days" with paper dolls and doll clothes! (That was just before Noah built the ark!
Once you've got a sketch of the pieces and they're cut out, start taping them together. Then bend them into the shape you want, stick a bit of tape to hold them in shape and go from there to work out how to put the rest together.
I've found it so much easier to take the time to get something visual out there in front of my eyes instead of having it kind of spin around behind them!
Good luck and let us know how it goes!