That's a tough question to answer, Jimmy, because of the variation of light in your subject and your relation to that light.. The only things I know to do (with the camera) to try and bypass darkening the photo are:
*Setting your camera's color option to vibrant (gives more vibrant colors)
*Using manual mode, or overriding your auto mode, and adjusting your F/stop down (smaller) a stop or two.. This will require you to slow down the shutter speed, as waterfield suggested, in order to get enough light into the camera.. Keep in mind F/stop and shutter speed work in tandem - when one goes up, the other has to come down and vice versa to allow enough light into the camera..
The added bonus of dropping your F/stop (and the funny thing is when you close your F/stop, the number of your F/stop actually rises.. for example F/2.0 is wide open while F/15 is almost totally closed) is that more depth of your photo will be in focus.. Wide open F/stop means your subject will be in focus - foreground and background will be out of focus.. Fully closed means your subject and the foreground and background will be in focus.. But, the more you drop your F/stops, the slower your shutter speed has to be, so don't go shooting race cars at F/15 with a shutter speed of 60 or 125 - your photo will be in focus, but he car will be completely blurry as the shutter didn't open/close fast enough to stop motion.
*Adjust your ISO to allow you to drop your F/stop (similar to using faster/slower film speeds back in the 35mm days)
*Adjust your white balance
*Bracketing - waterfield brought it up, but I'll explain it, in case you don't know what it is.. Bracketing shoots a series of photos instead of only one photo, when you pull the trigger.. the differences in photos are that, if I remember correctly, it will shoot two photos at F/stops lower than what the camera is set at, one at the camera F/stop setting, and two at F/stops above what the camera is set at.. so, you get like 5 photos of the same thing, but at different F/stop settings..
***which leads us to the NUMBER ONE way to darken and get more vibrant color in your OUTDOOR photos in the sun:
Buy a circular polarizing filter to screw on the end of your lens.. after you screw it on, go outside on a sunny day with the sun behind you.. look through the lens and start spinning the filter.. you'll know when you hit the jackpot because the sky (which is how I always use the filter to adjust) will become much more deep vibrant blue - as will other colors, but the sky is easiest to see.. then pop your photo.. The added bonus of this filter is that if you shoot water bodies or glass, it will remove the glare and the reflection from water or glass objects.. that's how I always get the DEEP blue/green water color (and blue sky) in my tropical photos - by removing the glare and reflection, like in this photo I shot last year..
Friendship is like peeing your pants.. Everybody can see it, but only you can feel the warmth..