It's not a tutorial; it's just a way to share "how I did it". All started when I was helping my Etsy teammate to enhance a little bit pictures of her items. I know that not everyone has Photoshop, and I found a convenient free tool for online photo editing http://pixlr.com/editor/ . Graphic user interface is pretty much intuitive and convenient to use. I'm going to use a picture of wedding flower from BelleBlooms shop on Etsy to show photo editing in action. Again, it's just one way to make your pictures look a little bit better. I'll show how I got the result (left picture) from the original (right picture).
Navigate to http://pixlr.com/editor/ and open an image that you want to edit from computer.
First, I've added contrast to the image. In the top menu, go to Adjustment -> Levels. A pop up window with histogram will open.
Look at the histogram. There are "empty" areas from the left and right. Move left and right toward center until histogram edges. Control what are you doing visually. Sometimes, it's better to move them even more to the center or contrariwise to leave some empty spaces on the edges o the histogram. Also, you can control brightness of the image by central slider. Play with them for better result. :) Confirm the result.
After those manipulations, I could clearly see that the image has slight blue tint. I corrected this with color balance that you can call from the top menu Adjustment -> Color Balance. Play with the sliders to remove the tint. Confirm the settings after you got desired result.
There is one more trick... Sometimes, you can get pretty much good looking image but background may be tinted a little bit especially in the corners. Usually, it's blue. In this case, you can just desaturate it with Sponge tool. Select the tool on the left panel. Select needed size of the brush, and it's hardness to zero on the top. Select "desaturate" in the drop down list, and set Strength around 50-70%. And simply apply the sponge tool in the areas where it's needed.
Also, you can add a little bit of sharpness. Call Unsharp Mask from Filter menu on the top and play with the settings until you satisfied.
These steps are easy. I wouldn't say they can make your images perfect, but they definitely may improve it. I got from this image...
... to this one.