Painting Hair in Photoshop
1. Getting Started
We start with a blank canvas, usually 2 - 3 times larger than the size you plan to show the finished product at and at least 200 DPI. Make sure you're not working in .jpg format, because .jpg will cause to you lose some of your hard-earned detail with each save. Also, make sure to save after you're satisfied with each step.
Now select a neutral tone (I picked a warm pinkish-tan here) and fill the background with it. A good tip, if you're not drawing the hair directly onto the face it's being made for, is to pick the most common hue in the face so you can see how well it works with the character's coloration. For Photoshop (on the PC), a quick and useful command to learn is alt + delete to fill layers or selections.
2. Outlining
After your background is filled with something other than glaring white, start blocking in the general shape of the hair on a separate layer, paying special attention to two parts - 1) Where it starts, and 2) Where it's ending up. For my own example, I'm not drawing it onto a character so it will just span from one corner of the canvas to the other to make it easier to follow. This is the only part where scribbling wildly without lifting the pen is allowed, so be sure to enjoy it.
3. Refining the Shape
Now is the time to pick how you want it to be; where the flyaways are, attachment point to the head, tips of the ends, etc. It doesn't have to be exactly how you want it to end up, but the drawing process goes a bit easier if it is. If you'll notcie mine, I've completely filled the area where the scribbles were earlier and put a few frizzies on the edges to make it more natural. I'm working in Photoshop with a pen and tablet set on size, not opacity. Those of you out there working with a mouse might have to play around with brush settings to find something you like.
Another helpful tip: Hold down the ctrl key to keep your brush from snapping to the nearest guideline / edge of the canvas while drawing, or just work in a larger area than you need and crop it down later.
4. Beginning Definition
This is a really small, almost invisible step, but helpful in that it allows you begin making a palate. Take the bottom half of the hair and lighten it, just barely. NOT with the Dodge tool! Until otherwise stated, the Burn and Dodge tools do NOT exist. This lightening can be done one of many ways, but the method I've done here is with the Hue/Saturation option. First, select roughly half the hair you have drawn so far with the Lasso then hit Ctrl + U or go Image > Adjustments > Hue/Saturation from the menu bar across the top. Once at the H/S window, click the checkbox for Colorize. Now play with the slide bars to make your selection just a bit lighter and a different color than the upper part and hit OK when you're happy. This color should be BARELY noticeable, such as my example below. Make sure to smooth out the edge where they meet if there's a line.
If you're doing this by coloring in a new hue over the first one, click the foreground color on the side bar to choose a new one. And don't just slide your little selector up or more towards the white; pick a hue closer to yellow from your current brown hue. Hit OK and start coloring - it doesn't have to be perfect, but should smoothly fade into the last one. Like I said in the last paragraph - it should be BARELY noticeable.
5. Defining Lights and Darks
Now that you have two different hues on your document, go into your color selector again and pick a lighter shade of the yellow, and a darker shade of the brown. Some people like to scribble a palate off to the side of colors they're working with - if this is you, you'll now have four colors. Take your light color with a very small (2 - 4 pixel brush) and start bringing it up into the darker one and visa-versa. Now move to your shades and lighten the lighter areas, and darken the darker. I like to leave the darker areas near the roots; it's where new hair grows from and thus hasn't had as much exposure to the sun, and also the place where artificial highlights grow out. *wink*
The most important thing here is to learn to let the pen skip a bit. Don't just draw straight lines from top to bottom; pick the lightest areas and let the pen skip and make short dots and dashes for a rougher look.
6. Deepening the shadows
You can see where the darker parts of the hair are from the last step, right? You DID remember to leave some dark parts? Good. Now go into your color selector again and grab a really dark version of the brown you have as your shadowed areas. Set your brush to about 70% opacity and enlarge it to near 25 pixels. Darken the already dark areas, but don't create new ones. If you want new areas, go back to the lighter shade and make a broad area and bring out the center of it with your new brown for a more natural look.
Shrink your brush down again to the 3-pixel area and go over the middle of the parts you just deepened to m