When you work with Srue, gets lots to start with (lots)... then cut up a load into the longer straight bits... and trim off all the bits sticking out with clippers... after that use a sharp knife and then a large file to finish cleaning up the bits sticking out so that you have really nice straight pieces to work with...
Then if you glue then one to one (flipping every second one over) you will get a nice solid and straight platform that is sturdy and looks like the bottom of the Landspeeder (rippled)...
Cut it to the shape(s) you need, and build away. Also use more sprue on inner egdes to strengthen them... For cutting the Speeder, try to work with one thats not already assembled... chop just behind the cockpit and use a Razor Saw if you have one, as its a long cut to make otherwise... once you have it stretched out, you will need more sprue to build a top frame, and I used Rhino Top doors (so they actually open/shut); but most anything would work (plastic card, cereal box, etc)... For the rotor, I used the lid of an old 5 gallon pail, draw it up first, and use tin snips if you have them (saves time)
Cheers