How to get more contrast in photos without photoshop?

I have a Nikon D3100, and it's my first DSLR and I'm still learning how to use a lot of the functions. I know how ISO, shutter Speed, and aperture works, and how stops work for the most part. However I find a lot of the time my photos don't have as much contrast as I would like, and I find myself playing with the "levels" on photoshop to give it a bit more contrast.

How can I up the contrast of photos without having to open them up on photoshop?

If you feel that this is a constant problem, look in the menus for "Set picture control" where you can customize any picture control by increasing contrast. You might find that you prefer "Vivid" to whatever you are using now.

Many of the ways to get more contrast in your scene have to do with working with and/or controlling the light.

Try shooting subjects that are lit from the side, especially from a low angle. For example, shoot things at sunset or sunrise. Those are sometimes called the "golden hours" of photography, because the light looks so much better than it does at high noon.

In order to increase the contrast of any image in the camera, you need to control the lighting of the scene.

When you shoot on overcast days or in the shade, the images will by nature have less contrast.

Until you can begin to "see" the light and notice the lighting ratios between the highlights and shadow areas, you will have to depend upon post production to make changes in the native image files contrast

Many photographers shoot in RAW and make minor changes in contrast of all the images shot under the same conditions. This is done in bulk, using Lightroom

Before doing anything, make sure you're reviewing/editing your photos on a properly calibrated monitor! I can't tell you how many times I've heard from friends/family etc. "My pictures always come out so dark, what can I do?" Or, "My pictures look really faded, what can I do?" I go over to their place… Sure enough… They've got the brightness Way down on their monitor, or Way up. OF COURSE their pictures are going too look dark if their monitor is too dark, or really faded if the brightness is too high, or the contrast is set wrong.

If your pictures lack contrast, make sure your contrast is properly set on you monitor first. Either buy a proper monitor calibration device, or, download free monitor calibration software, or at the very least, use an on-line monitor calibration chart.

I can't stress enough how IMPORTANT proper monitor calibration is. And A LOT of new photographers completely overlook it.

Ultimately the amount of contrast in an image is down to lighting. Learn how to control the light your photos if you want more contrast.

Also using lenses on wide open apertures has a tendency to make images soft. If you want better contrast set your aperture to either f/8 or f/11

It's all about light. Learn how to gauge the light.

This is where your ability to shoot in RAW [Nikon call it NEF=Nikon Electronic Format] has value; once you have the image access it through Nikon View - a copy of which comes with the camera - and use the Colour Balance / Contrast slides before accessing either the the Nikon Capture or Photoshop editing suites.