Welcome to Gaia! ::

good luck with that

Well, if you can't sew (and really even if you can) the best way to start a project like this is to hit some thrift stores or old closets or whatnot and look for clothing items that can be altered / tweaked to suit the costume. Especially for regular clothes (but not so much armor) Don't understimate hot glue!! I use it for tons of things, and it makes adding detail to a costume really easy. Cardboard is also useful, especially for these big boxy mecha type costumes, but you've got to remember to COVER IT with something. You can't just paint it or (god help you) color it with markers or something. Stay away from foil too. But naugahyde / vinyl fabrics, soft plastics, thing like that work really well. The most important thing to remember is to keep in mind the size and shape of things. Think about the texture they would be and try to mimic it. That's probably the best general advice I can give. Just think of what materials are accessible to you and be creative.