This is 'Sleepy Cat' - my latest embroidery project, and my own design. I've sewn mine onto a cushion that's approx 18" square, but the motif can be scaled up or down to suit your own needs.
I traced the design onto my cushion using an ordinary pencil - as my cushion cover was made of 100% cotton, it was fairly easy to sponge any stray pencil marks off with a cotton bud, some detergent and warm water when I'd finished - then, using 10 or 12 varying shades of cream, orange and brown embroidery threads I began to fill in the shapes.
I tried not to repeat a pattern more than once, or if I did, to use different colours or stitches, so no two were identical (apart from the toes and facial markings) I was planning to just embroider the heart shape too, but then found a leftover wooden button that was exactly the right size, and made an interesting feature.
The main outline was done in stem stitch, and the outlines of the shapes within are mostly stem stitch or chain stitch, as is a lot of the filling in. The rest is a mixture of leaf stitch, blanket stitch, open fishbone stitch, fly stitch (worked horizontally instead of vertically) and vandyke stitch. Mostly I used two strands of thread, but for the really fine details, like the whiskers and the pale cream curls and lines between each shape, I used a single strand.
Below is the original drawing I used as a template. It could be adapted in any way you wanted, maybe using just the basic outline with different shapes to fill it, adding beading, appliqued fabric, more buttons, sequins, or ribbon trim. Just let your imagination and your needle run riot!