Photoshop has a huge laundry list of commands, most of which one may ignore to their hearts content. I assure you that the 3 commands one should learn to master are layers, levels and curves. Layers is the most important thing to get used to using. Levels allow one to adjust color casts, dynamic range, and overall brightness in the photo. Curves enable one to pop colors, contrast and create color shifts that the most ardent user of psychotropic drugs can fall in love with.
Using a layer for each and every adjustment allows you to make changes to your finished product, without losing the original starting point. Making the layer is very easy, click on the half moon shaped circle at the bottom of the layers palette. Choose what you wish to adjust. Before I close out the adjustment marker, I often save the adjustment for future reference. Layers enable you to play around and have fun without ruining your original.
I use levels to set up the primary values my photo will have. I remove the colorcast from within the shadows and white areas. This is done by using a color picker in the area I want my deepest black and my whitest white. The end points are adjusted for each individual color to make the black black and the white white. I adjust the center slider to emphasize the midrange values in the manner that pleases me most. This gives me the starting point for all my work regardless of whether it is a straight on, multiple exposure, or a psychedelic photograph.
Curves are a bit tricky. For a straight photograph and most multiple exposures, I usually make a flattened S curve out of the normal line of the graph. This improves contrast and makes the color pop a bit. It is when making an abstract or psychedelic print that curves are used in a radical departure from this method.
I often start a psychedelic prints curves by taking one color and inverting the slope of the graph. This makes the lightest shades of that color dark and the dark shades light. If one color change doesn’t create the effect I want I sometimes go with a roller coaster effect on several colors and sometimes on the combined graph. The idea is to make the color so dramatic that the actual shape of the object becomes a blur to your eye. Have fun with it.