Hey folks!  A lot of new artists ask what they can do to make their art better.  The standard answer to this question is 'practice', and it's completely true.  That being said, perhaps you find yourself in a situation where you're a programmer with little or no art experience, and you need art for your project.  You can't afford to hire an artist, you can't find someone willing to work on your project for free, and you'd like to make a game that looks at least passably good without spending thousands of hours practicing art.  If that's where you are right now, then this tutorial is for you.

One of the things I've figured out as I've dabbled in art is that sometimes you can improve your art leaps and bounds just by learning and applying certain things immediately.  This tutorial will cover the things that I've figured out over the past few years that would have been handy to know earlier on.  As people leave comments and tips, I'll try to add to it.

Before I begin, though, an important caveat:  Ultimately, the way to get really good at art is to practice.  There's really no way around it.  Nothing I'm saying here will turn a beginner artist into an advanced one -- rather, the idea is to understand your skill limitations and work within them while applying some knowledge that most beginners aren't aware of.  Have fun, and good luck!

If, while reading this, you think of anything that could be added, please reply and I'll consider adding it.

Color Theory

A lot of programmers who are just getting started with art tend to think of color in terms of red, green, and blue.  This is a horrible way to think of colors if you want your art to look natural.  If you haven't done this already, the absolute first thing you need to do is start picking your colors with HSV sliders as opposed to RGB ones.  RGB sliders tend to lead people to make unsubtle color decisions, such as using pure green for grass, etc (this is one of my personal pet peeves; it's so easy to choose a natural color for grass, even for a beginner, but som many people just pick #00ff00 and end up with really unnatural-looking grass).  Note also that it's better to draw over a grey background than a white one, when picking colors, as a pure white background can skew your color choices.

To get a bit further into the color thing, you need to know a couple of basic things about light and shadow.  In a natural environment, light and shadow have their own colors.  If you're standing outside in broad daylight and look at your shadow, your brain tells you that the color of your shadow is just a darker version of the surrounding color.  This isn't actually the case.  In reality, on a sunny day, there are two major sources of light:  The sun, which is yellowish, and the sky, which is bluish.  Your shadow is still receiving light, or else it would be pure black.  That being said, the reason you have a shadow is because you're blocking the sun from hitting that area, so the main source of light to that area is going to be the sky.  As such, shadows tend to be more blue than the surrounding area.

This is of course different on an overcast day, or when you're inside (because the ambient light in the room is the color of the walls an ceiling), but as a general rule for beginners, make your highlights a bit more yellow and your shadows a bit more blue, and you'll end up with art that looks significantly better than someone who doesn't already know this.

Use Photo References

Short of actually tracing a photo (or pasting content from the photo into your art), it is always okay to use photos as references, even in finished art.  That being said, I would stop short of encouraging anyone to just paint or draw exactly what they see in a photo.  Look at a number of different photos and combine elements from them into what you want.  If you're drawing a person, it's fine to look around until you find a photo of a person with the correct pose and body type.

Note that since you can't get in legal trouble as long as you don't trace, it's also fine (and encouraged) to credit your reference photos.

If the photo is released under a Free license, it's also okay to trace the photo, but understand that in that case your work is a derivative work and you need to follow the terms of the license.

Everyone wants to be able to draw awesome stuff right from their imagination, but that is one thing the definitely takes tons and tons of practice (artists will often talk about having a 'mental library' that they can use).  You need to remember, though, that what's important is the quality of your ultimate result, not how you arrived at it.  DO NOT BE ASHAMED OF REFERENCING PHOTOGRAPHS.  PROFESSIONAL ARTISTS DO IT.

The Pen Tool

Tablets are great, don't get me wrong.  If you're going to be doing serious artwork over a long period of time, I would strongly advise you to get a tablet.  However, it's also important to note that a tablet is only as good as your drawing arm (practice, practice, practice).  If you're one of those people who has a bad arm but a good eye, then the Pen Tool is your friend.  Advanced drawing programs (Photoshop, GIMP, Krita, etc) can generally stroke a pen line as if you're using a brush.  Hence, if you have time, you can assemble something line by line making adjustments with the pen tool, and end up with a result that's nicer to look at than if you'd painted it directly.  If you use a vector drawing program (like Inkscape), you can continually make adjustments to your strokes as opposed to being stuck with them once you're done.  If you're not a fan of the vector style, you can always start in a vector program and then go to a raster program once you have everything drawn out.  Some raster programs also let you work with multiple pen strokes, so you can accomplish this without using a vector program in some cases.

Layers

Use them.  Seriously.  Have a white background layer, then paint on the layer above it.  Have shadow and highlight layers.  Don't paint on your rough sketch layer, particularly if your sketch layer is a scan of an image.  You don't want to have to clean up pencil lines in your final work.

Brushes

Use a mostly solid brush with a slightly soft edge, as opposed to using a brush that's completely soft.  Brushes that are soft all the way to the middle look terrible when you use them to fill an area, because the area gets filled incompletely.  Using a solid brush also helps you to think of your shading and highlights in terms of solid areas rather than lines.  You'll break this rule later, but it's good to follow it as a beginner.

Art Programs

Use whatever program that gives you the results you like the best.  Certain programs act in different ways.  Try a bunch of them before you make up your mind.

"Cheating"

When you set out to make art, it's important to think about why you're making that art.  If you're making creating it in order to learn, then you probably want to do things the hard way, and force yourself to grow.  If your purpose is to make a piece of art that looks as nice as possible with your existing skill set (say, for a game), then you should strongly consider "cheating".  I'm not talking about doing anything illegal here (such as plagiarism) -- what I'm referring to as "cheating" in just the act of using your tools and resources to your greatest advantage without regard to purism or doing things the "right" way.

There are a number of things you might do in order to cheat. 

For interiors, particularly futuristic ones, if you have some amount of skill building 3D environments, then grab a program like Blender and build your interior in there.  Render it with cycles (or some other engine that supports physical lighting), and then paint over the entire thing with digital paints so that the original render doesn't show through at all.  In doing so, you've just effectively "cheated" and allowed a computer to figure out your perspective and lighting for you (both of which can be difficult for a beginner to do realistically).

Also, there's nothing wrong with painting over a photograph (provided you have the license to do so, and give proper credit).  If you need a digital painting of an outside environment, search Flickr (or some other website where you can find CC-licensed photographs) and find an image that you like, then paint over it.  Remember, if you're making art for a game, you're concentrating on the end result, not the process.

One tip for paintovers and blending in general -- your paint program probably has a hotkey that you can hold down that changes the brush tool into the eyedropper tool.  If you're painting over a photo or trying to blend colors, learn to use the hotkey without jumping to your toolbox every time you want to switch.

Modern paint programs are good allowing you to distort things in very specific ways.  If you want to paint ground, for instance, you can paint a splotchy pattern in the general color scheme that you want, and then use your paint program's perspective transform to make the ground look flat.  If you watch videos of people speed-painting environments, you'll see this a lot.  Another thing you can do is if you draw something and aren't satisfied with the proportions, you can use the transform tools to tweak the proportions of whatever it was you drew (be it a person, an object, or whatever).  This is of course better done in the rough phase, so the inevitable ugliness left over from the transform won't be part of the final product. :)

Practice :)

In the long run, if you want to be really satisfied with your art, practice is the only way to go.  That being said, practice has a lot more value if you understand what it is you're trying to get from it.  As an artist, you need to understand the visual tricks that your brain plays on you, and be able to see the world as it really is (the light and shadow thing from above is an example of this).  When you draw the world, think hard about what you're observing, and make special note of the things where there's a difference between what you think you see and what you actially see.

Resources

• http://2dgameartforprogrammers.blogspot.com.au/ -- A must-read blog (and OGA contributors, too!)
• http://www.morguefile.com/ -- An archive of photos that are safe for use as references