An Hour of Wolves and Shattered Shields has a set of free Roman Shield designs for decals. Just print them out on decal paper, or on regular stock and glue them to the models. I should think that a hobby product called Modge Podge would handle that task well.
The Paint Machine Blog has an excellent, multipart tutorial on painting ancient spanish scutarri. A nice touch is that he tells you how long it takes to paint each step.
If you’ve been inspired by the Iliad and the Odyssey, or by movies such as Ray Harryhausen’s Jason and the Argonauts and Clash of the Titans, or by Troy, or 300, or any of a myriad books or movies on the Ancient Greeks, you’ve probably (like me) considered building a couple of armies to act out your swords and sandals fantasies. Ancient Greece is a website that provides a wealth of information of the history behind the legends.
Over at MacPhee’s Miniature Men, there’s a tutorial on painting a Roman Legionary with craft paints. While I’ve found the craft paints to be of varying quality, they DO have the advantage of being very cheap compared to the Games Workshop, Vallejo and other “miniatures specific” paints.