Hello, i was wondering if someone could help me out by suggesting what plugins and tutorials i need to be looking at in order to create spaceships and robots?
I learned SU by doing the official tutorials found here http://sketchup.google.com/training/videos.html
They cover just about anything you need to know.
As far as plugins go, I don't use any for modeling and yes I do robots/spaceship things. If you are just getting into modeling then I recommend you don't use any plugins. SketchUp can do anything you need but plugins can make some operations easier. Keep in mind that by the time you are comfortable with SU you'll probably already know why you want a plugin and for what operation.
I endorse what both parker17 and Chirp Chirp said.
I try to avoid it but I use plugins from time to time. The ones I use more often are :
Joint Push Pull
Soap Skin & Bubble
and few others that I use even more rarely. It all depends on the exact result I'm looking for and on how much time I have
My advice would be to stick to standard SketchUp tools and learn them good, trying to solve problems with them, asking for help on forums and experimenting a lot. As Chirp Chirp said, you'll know which plugin you will truly need as soon as you'll become comfortable with SketchUp and its native tools.