- draw two ovals, slightly overlapping
- connect them with curves as shown

- draw the legs using overlapping ovals and curves
- draw bumps over the eyes

- Add the eye, nose and mouth
- draw the feet, making the toes fat at the ends

- erase parts of lines to make the body parts join up as in this picture. You might like to trace it onto a fresh piece of paper.

Here's the frog with a touch of color quickly added with a basic paint program. It just took a couple of minutes with a flood-fill green, a spot of yellow with a paintbrush tool and using lighten and darken to add highlight and shadow.