Cut out the basic Yoda outline from cardboard - the thicker and stiffer the better. Using that as the base cover with lots and lots of newspaper strips soaked in flour and water glue. I've always just used this glue mix for papier mache and it's been cheap, easy and dried and stuck just fine. You could add pva glue to the mix instead of flour though.
I tend to leave it to dry inbetween layers rather than build the whole model up at once as it then takes ages to dry through. Add shape / sculpt the model as you go and if you are going to want it to stand up unsupoported then ensure it can do so by shaping the base as you go.

Once you have finished making the papier mache shape and it is totally dry you can start to paint. Again patience is the key here, letting each colour dry off fully before starting the next coat. I use acrylic paints for deep colours and good coverage, but you could use poster paints and do more coats.

Once the paint is dry if the figue is something quite detailed you might want to draw in that detail with black pen (or paint in fine detail if you are handy with a paintbrush - I am not!). For Yoda I also used some silver paint for face detail such as wrinkles.

Finally to give the figure a glossy finish and help preserve it I add a final coat of clear varnish. Be careful at this stage that your varnish doesn't make the paint or pen run.