Q:

What techniques has Jennifer Tibbetts used to make her photos "pop"?

I am just getting in to photography (as a hobby), and both me and my wife really like the style this photographer uses. See her website for some examples.
I don't know how to describe it other than it is almost a bit foggy (especially in the 2nd one), and sometimes it looks like the background is washed out; yet the color still really pops.
I'm not asking to re-create the effect. I just want to learn what techniques are being done, so I can adopt something similar, but tweaked for my taste. 

A:

Although post-processing may have been involved, it is not necessary. What I see:

Shallow depth-of-field: Means a bright aperture, F/2 or brighter most likely. This is a type of lens you buy and the photo has to be shot that way. It creates separation between background and foreground.
Over-saturated colors: Most cameras now have different color modes and image parameters in the camera. If you select Vivid on some cameras you will get colors such as those or worse! This you can easily do in any image processing program. Look for a slider called 'Vibrance' or 'Saturation'. Be careful that it does not affect skin tones though!
Light modifiers or artificial light. Again, this has to be done at the time of shooting. You can use a reflector or off-camera flash directed at darker areas of the photos. This is why you do not see any strong shadows on two out of three of your examples.

A:

Apart from what others have already answered, i also noticed that there are very few colors in the photos but they are contrasting in nature. Red against Green background, Blue and Red against yellow-green background. So the setup itself is adding to the overall color contrast of the image.

