Nikon D5100 with 18-55 tips?

I've always been interested in photography, and i'm pretty good with post photo editing (Photoshop CS5: D) but all my unedited pictures are just bland. Any tips?

One I might give you. Get into your settings and bump your camera's contrast level by a couple of notches. I've done that with both my Canon dslr cameras and I'm liking the look much better.

Are you using the camera in Auto modes?

Try switching to spot metering, rather than matrix metering and shoot in manual - that way you will have control over the exposure, not the camera.

You have not said whether you are shooting landscapes, nature, sports or portraits - for landscapes, visit the scene when the light is good (scout out before hand if needs be during any weather). The 'golden hours' at sunrise & sunset are the best as the low angle of the sun and the warm colour temperature adds texture & tone. Midday light, when the sun is overhead, looks too 'clinical' and is a flat light.
The Photographer's Ephemeris;
http://photoephemeris.com/
is a great free resource to help you plan when/where sunsets/sunrise will occur at a particular location.

For portraits, use large light sources to soften shadows. Try to get a sense of shadow to aid definition of shape. You may have to consider investing in a speedlight or two to use off camera to add a little 'punch' to your lighting.

Sports can be more difficult to light - you have limited options of when it is & where you can stand.

The secret is getting it right in-camera so Photoshop wouldn't be necessary. To do that, you must learn photography to be able to get the correct exposure right from the original scene you took a shot of.