i agree with what the above comments stated. My only comment to them is to post an image to help explain (an example) of what they are talking about. since they didnt I am posting with an image that was edited from color in PSCS2, by removing 2 of the color channels. You dont have to use any tool, just pull all of 2 colors channels out.
In addition to the above comments (or maybe they already said this...) I think it would not have looked so flat if it were taken at a different angle. Being outside, with a wall behind you, it is hard to create that depth (whereas inside a studio you have lights to your advantage)
but those are just my two cents, cause like someone said, these images have much-o potential! keep up the good work! If you do anything else with these, or try anything different, make sure you post it so we can see!