Q:

How to structure image directories for SEO?

We are currently reorganizing some files on our site, and I am trying to figure out the best way to organize files to be SEO friendly.
Here is the wrong way to do it:
yamaha-bikes\yamaha-bikes.php

The right way:
bikes\yamaha-bikes.php

My question is how do I go about organizing images for those products? 
Obviously if I throw a million bike images in my folder, it will be very disorganized, but would it be SEO friendly?
In other words, should I do:
images\yamaha-bikes\yamaha-bike.jpg
images\yamaha-bikes\yamaha-bike2.jpg

or 
bikes\yamaha-bike2.jpg

Obviously the first option is easier to organize, but is it as SEO friendly?

A:

I would consider having more descriptive names, for example:
images/yamaha/yamaha-gladiator-bike.jpg
images/yamaha/yamaha-YZF-R15-bike.jpg
Remember that "-" are usually treated as spaces so you have the best description that would probably match what a user would search.
Also consider also importantly to use good ALT tags in the IMG that you use to link them to reinforce the name.

