Jump right into your old foundations text - especially if you have Das' Principles of Foundation Engineering.  Plenty of examples there.  Otherwise try Foundation Engineering by Peck, Hanson and Thornburn (PHT) also good examples.

Try to limit your design to two sections, one for max height or the highest quarter point and one for the smaller wall height.  That way if for no other reason you can work out the different details between the two.

Also try to keep the footing thickness the same varying only the footing width.

Das has a sketch dedicated to thicknesses for each element of the retaining wall based on retained height so this is great place to start.

As the wall is relatively low also try proprietary systems such as timber or concrete crib walling or gabions or maybe porcupine walling for lower sections?  Design is simple, from tables etc or can be designed by the supplier.

You may want to check out the many precast block style retaining wall systems that are now available.  Keystone Block systems are one example (of many).  They all use stacked interlocking blocks which allow free drainage of the backfill through the wall, thus reducing loading from water pore pressure against the back of the wall (as in a traditional retaining wall).  The higher block wall systems utilize geotechnical fabrics and earth backfill to add support to the walls.  These walls have a pleasant finished appearance and can readily placed around curves and varied in height.  The are becoming very common and you might even find the materials available in places like Home Depot.  The companies can provide you will design and engineering manuals, but if you have any unusual soil conditions or serious site conditions, such as closely spaced house, you may want an experienced designer to look at it.

Alright GeoffD, what the heck is porcupine walling?  ;)

Purcupine walling is a proprietary block walling system with longitudinal ridges on the top which interlock with grooves on the base of the next block. When viewed end on the ridges make it look like a porcupine or hedgehog (with a stretch of the imagination)  also good fun to leave a phone number of the local zoo and ask a colleague to phone up and make enquiries about porcupine walling - get them to ask for the Technical sales manager Mr. C. Lyon.

Seriously check out www.mmgces.co.uk