When you decide you'd like to paint, you will likely encounter the art myth that it takes talent. Don't believe it. The desire to learn to paint and enthusiasm are what you need more than anything else.
Having decided you'd like to learn to paint, you need to decide what paint you're going to use. The four main choices are: oils (traditional or water soluble), acrylics, watercolors, and pastel. It's a very personal choice, and if you don't get on with one type of paint, be sure to try another.
I believe in buying the best quality paint you can afford that still lets you feel you can play with it. You need to feel able to paint over something that's not working, or scrape it off if you're using oils, rather than desperately trying to keep it because of the cost of the paint you've used.
Color mixing is something beginners often shy away from (especially when it's labeled “Color Theory”). Don't, the basics of color mixing aren't particularly complicated. Embrace the challenge (and fun) and get color mixing. At worst you'll produce mud colors, and if you don't want to waste the paint by throwing it away, you use it with some white to do a monochrome painting or value exercise.
Ultimately the degree to which you plan out a painting depends on your personality, some people find it essential and others a hindrance. But regardless of how detailed you like to plan (or not), there are several decisions that have to be made before you to start to paint, including what you're going to paint (the subject), what format and size the painting will be, what you're going to paint on (called a support), what technique you're going to use, and what colors.
Ultimately the degree to which you plan out a painting depends on your personality, some people find it essential and others a hindrance. But regardless of how detailed you like to plan (or not), there are several decisions that have to be made before you to start to paint, including what you're going to paint (the subject), what format and size the painting will be, what you're going to paint on (called a support), what technique you're going to use, and what colors.
by Marion Boddy-Evans
Source: http://painting.about.com/od/paintingforbeginners/a/first_painting.htm