If you are just starting out with oil paint, I have some advice.
First, be realistic. Don't think you're going to make any masterpieces any time soon, and never think that there are any shortcuts. If you just want to play around and don't care about developing real skill, then just do that and have a good time. But if you are serious about learning to paint well, realize this: while it's not that difficult to learn how to make mediocre paintings that your mom will like (or tell you she likes), making good paintings is hard—really hard. It takes a lot of practice, regardless of talent, to learn how to paint well. You will make many bad paintings before you make your first good one. If you are someone who can't stand to be bad at something, over and over, before you get good, then oil painting isn't for you. Maybe you should try video games. You can find cheat codes for many of them that will make you invincible.
Second, keep it simple. It’s counter-productive to plan complicated projects until you have the skill to pull them off. Your subjects, to start off, should be simple. An egg, a mug, a tree. No people. No copying photos. Your goal, to start out, should be to do some bad paintings that no one will want to look at. If your goal is to make bad paintings, it won't be too hard to get there. After ten of those, you can start to think about paintings that are...less bad. You’ll learn more, in the same amount of time, by making several simple bad paintings than by making one complicated bad painting.
Third, there is no reason to start out by spending a lot of money or getting fancy with materials. Get a few tubes of decent, artist-grade paint. Don't get student grade, don't buy a beginner's painting set, and don't buy water miscibles or other convenience oil paints. A good starter palette would be titanium white, ultramarine blue, burnt sienna, raw sienna, and ivory black (you can get these from Robert Doak for well under $40—but don’t let him sell you anything else). Those pigments are all inexpensive and non-toxic (not that you should eat them). You won't be able to make bright, high chroma paintings with this simple palette, but that's a good thing: until you learn to mix neutral colors, a high chroma pallete would only force you to make luridly nasty paintings. Get some small primed canvases (no more than 8 x 10") or some of those primed canvas pads. Get some brushes—I'd suggest a couple of bristle flats about as wide as your thumb and some synthetic sable (soft) flats about as wide as your pinkie (if you have particularly wide or narrow fingers, adjust accordingly). Also get a pack of cheap plastic palette knives. Get a pad of disposable paper palettes and a big roll of paper towels. For cleaning brushes, either go to the hardware store and buy some odorless mineral spirits, or go to the art store and get some linseed oil. Get a basic easel—a cheap table easel will do. If you continue to paint, you'll be upgrading all of this stuff. If you find that you hate painting, find a niece or nephew to give the stuff to.
Fourth, learn to handle the paint. Set up your easel and a blank canvas. Squirt a little of each paint onto the edges of your palette. Make an abstract painting that doesn't look like anything. Play around. Until you get used to oil paint, you may find that it’s sticky and hard to manage. Don't thin your paint down to make it manageable; never add more than a tiny bit of oil or solvent to the paint. Learn how to load paint onto the brush; not too much, not too little. Learn how to make a flat area of one color that isn't streaky (hint: don’t be afraid to scrub the paint into the canvas with a bristle brush). Learn to make definite strokes; never dab it on. Mix two colors together with a palette knife—try ultramarine and raw sienna. That makes a gray. Add some white. That makes a light gray. Try mixing every combination of paints on your palette to see what colors they make. Learn how to make darks without using black (I’ve done many paintings in which the darkest darks were a mixture of ultramarine and burnt sienna). Black is a good mixing color, but it’s of limited utility for making other colors darker. When you make a mistake, learn how to scrape the paint off with a palette knife, wipe off the remainder with a rag soaked in a little bit of solvent, and start that section over. Learn to blend two colors, laying down two adjacent tones of paint, then using a soft dry brush (cleaned every few strokes) to feather between them, gradually developing a gradation. Use multiple brushes at a time—one for each color, or at least one for darks and another for lights. Learn how to apply light paint over dark paint (or dark over light, which is harder) without having them mix more than you want to and getting all muddy. This last skill takes a very light touch and plenty of practice.
Fifth, pick a simple subject and try to paint it. You may want to start with just a painting in one color, using just shades of black and white, or burnt sienna and white. Try a painting with just ultramarine, raw sienna, and white. You won’t be able to mix every color you see, but, in fact, you can’t do that no matter how many colors you use. Don’t drive yourself nuts with arbitrary limits, but try to make your first few paintings quickly, in an hour or two each. It doesn’t matter if they are any good, and if you are trying hard to make good paintings you’ll be too frustrated to continue. Your goal is to make some bad paintings that no one but you will ever see, learning from each one. Finish a painting, put it away without thinking about quality, and move on to the next one.
Sixth, after you’ve done ten or so small bad paintings, take a look at them. Are the last ones as bad as the first ones? What have you learned to do well? What is still embarassingly bad? What do you need to learn next? Understand that your own perception of your work will tend toward either absolute enchantment or utter loathing (often with rapid swings from one to the other). Learn to appraise your own work realistically. Try looking at it in a mirror—that sometimes helps. Find someone you trust to give you honest but not excessively critical feedback (but decide for yourself whether they are right or wrong).
Seventh, save up some more money and get some more supplies. You probably want some more colors. Add them to your palette one or two at a time after experimenting with how they mix with the other colors you already use. Try some zinc white, which is much less overpowering in mixtures than titanium. Try cadmium red or cadmium yellow. Learn about pigments and choose paints that are made with only one pigment (you don’t need paint companies to do your mixing for you). Get some more brushes. Think about a better easel. Think about better surfaces than acrylic primer. Think about making some panels. Think about more complicated subjects (but not too complicated). Look at good paintings by artists you admire and think about how they might be made. Are there any painting classes you could enroll in? Read the rest of this web log, other web sites, and books to learn more about what you can do with paint.