I'm by no means an expert, and I encourage any mod to edit this, but since paint is so expensive, I figure I should list a couple ways you can save money on it.
1. Start with a limited palette. See how many colors you can mix with just three or four paints before you go on to others. The more exotic the color, the pricier it will be.
2. Know how much to use. Acrylic paint dries fast, especially if used sparingly. So, painting with large amounts, while seeming to be wasteful, actually prolongs your work time and can ultimately use less paint. Oil paints can be used a tad more sparingly. Watercolors can be placed on a palette and allowed to dry, and still reused indefinately - never throw out dried watercolors!
3. Buy lots of brushes. try and have one brush for each color you blend. It keeps you from having to remix a color over and over again, you won't have to wash your brushes so much, and your colors won't muddy so quickly.
4. Don't mix large amounts of one color into another! If you want an orange, don't add two big blobs of red and yellow. Start with a blob of yellow and add tiny dabs or red till you get just the right hue - and check as you go by dabbing a touch of it on your canvas where you want the orange, and see if it's good. Once you go overboard on one color, you have to add more of the other and back and forth until you've wasted it all. With time you'll be familiar enough with your colors to better guess how much to add.
5. Oil paint stays wet so long as it isn't exposed to air. So, if you keep your paints on a good palette, preferably a thick glass pane, you can saran wrap it (and I've even heard freeze it in your fridge).
6. Keep painting! The best way to save paint is to get as much as possible always on your canvas. Any time it dries, either on your palette or brushes, that's wasted paint - anytime you clean your brushes, that's wasted paint. If you were to paint with oils nonstop, then theoreticaly you'd never have to wash a single brush.
7. Keep your area clean and organized. Any paint you get on yourself, the floor, the easel, brush handle, etc, is wasted paint. The second you see a mess, clean it up, and see if you can't get some of the paint back on your palette. Paint loves to make a mess, and once it's on your hand, it's bound to spread throughout your home, car, pets, etc.
HOW NOT TO SAVE ON PAINT
- buying some crappy student brand that doesn't mix, dilute, apply, or dry properly, leading to endless frustration.
Hope this helps!