This tutorial is actually more a collection of useful tips about digital painting which, I believe, all people starting out in this area should know.. It's based on my old tutorial but highly expanded and with many more tips and pictures. I used the same picture to show the progress although not because it's perfect but because it's got some flaws, correction of which is an important part of this text.. I hope you'll find it all useful :)
First things first. Idea and reference pictures. I use them whenever I try to paint something more realistic or something I never painted before, just to make sure all the proportions, lights and such are okay.. Lately I actually don't use any direct references, I only look up certain parts of things I need (for example a photo of some specific kind of flower or the way feet may look from some angle) but in this case I'm using an older artwork to show the creative use of a whole photo as a reference.
And here's the tricky part - do NOT paint ON the pictures.. The result may seem better at first but it won't teach you anything.. Not to mention it's usually very easy to tell the picture was over painted or traced, especially when you're fairly new to digital art (and nobody likes cheaters ;)).. Most of the time I rarely look at the reference photo's but when I do, I'm just checking if everything looks all right.. Some of them, like this girl's pic here, I'm putting in a small version on a different layer. In this case I needed that to base the shading on something.. Smaller version are better - stops the urge to paint on the picture ;) and you can move it to the place you need to focus on..
Another tricky part is - never try to copy the picture very closely.. There's no reason to do it, it will just look as you were painting on it. Make a sketch while looking at the photo, but never directly on it. I'm using all my references exactly as.. well.. references.. Look at the photos and my pic - it doesn't look like a photo manipulation.. Which is good.. unless you want to make a photo manipulation, but in this case you chose the wrong tutorial ;) Although while looking at this artwork now I can tell that I followed some of the lights on the reference pictures too blindly and left the general lighting of the image too unspecified in many place
As for choosing the photos.. I do it before and when I'm painting.. Just because I never really have a strict concept.. The ideas come and go while I'm painting. My magical source of photos is http://images.google.com
;).. In this case I typed various words like: "swamp, moon, moon sky, dusk, water lily". I've ran through thousands of photos which is handy as it also taught me a lot about colours and how they mix together.. A good idea is to open some pics in Photoshop (or some other program) and check colours with the eye dropper tool.. You'd be surprised how different colours make a good colour scheme.. Or how similair colours give you big contrasts.
And now for something about the program in which you're going to paint the picture in. I painted this one in Open Canvas, using watercolor (with various settings of opacity and flow) and the pen tool, but it can be done, exactly the same way, in Photoshop and Painter (right now I'm actually using Painter 7 and have been for many months, doing some minor touch up's in Photoshop later, so I can guarantee it's not THAT important which program you're using). If you're painting in Photoshop the matching tools will be some standard brush with settings changed depending on what you're painting.. For details it'll be a small brush, with high opacity and flow, for painting the body and the background it'll be a big brush with small opacity (like ~30%) and small flow.. It's not like you can paint a picture using only one brush.. You have to keep changing the size of it often in any program you use (doesn't matter if it's Photoshop, Painter or Open canvas).. NEVER use dodge & burn tools to paint your pictures.. this is a common newbie mistake because it's so easy and looks so nice at first but look- you're not really painting with it, you're just making only ONE colour darker or lighter and there's no such thing in nature that consists of only one shade. Remember that digital painting is PAINTING, not using some magical tricks and brushes ;)