I know that there are loads of tutorials on UV Mapping but there arent any advanced ones, theres loads I'd like to ask about say wings 3d but im prolly going to try and work it out myself, I have made this model and I am finding it very difficult to UV map it, can anyone give me help with this? its my 2nd model, I want this one to work lol

EDIT : It may seem like some edges are joined but there not, the wheels, body and cannon are seperate