Wrought-iron and wicker are popular choices for outdoor furniture because they age well and can stand up to the elements. Plus, they can both easily be painted to fit your decor.
If your space is too small for a full patio set, be sure to have at least enough chairs for guests and then create a make-shift table.
An old door or piece of plywood balanced over two apple boxes or paint cans will do just fine. Cover it in a funky piece of oil cloth or other wipeable fabric and let the fun begin!