The medium you create to choose your art has a substantial impact on the look of the final piece in a hobby or profession in which subtle details can make or break the image you intended to portray. For beginners, here are the basic differences between the mediums, or in regards to painting, the types of paint:
Watercolor is the cleanest, simplest type out of the “big 3” paints. It is similar to the simple paints we all used as children, where we would dab moisture onto a solid block of pigment then brush it onto paper. Watercolor has a very light, opaque texture and colors blend very well because of this. It, like the other paints here, can be used for just about anything, but often its used to get that light, bright, “jazzy” look of a sweeping landscape. It’s also common to use watercolor as background for other mediums because of its neutral final appearance. Disadvantages are the difficulty in adding depth or executing very dark, rich colors with such a light, thin, and perky-colored substance.
Acrylic, while a bit messier than watercolor, is still a very clean medium. It is much younger than traditional oil and known for its tight, vivid final appearance. It does just about everything well and can be utilized easily in mixed-medium paintings. Its disadvantage compared to oil is that, without additional additives, it usually dries much more quickly. This reduces the artists ability to continuously perfect a painting for days or even weeks as they are sometimes able to with oil, but that may be desired by a painter who finishes their work in a matter of hours or a single day. Examples of acrylic painting are often seen in science-fiction art, aviation art, and other types where fine lines and tight texture are desired or required.
Oil is the traditional “fine art” medium and a true joy to work with if the artist enjoys long, drawn out painting sessions with detailed color blending and creative texture techniques. It is capable of incredible darkness and depth and chances are if you look at a painting by one of the “greats”, or a famous historical portrait, it was done in oil. Considerations or disadvantages include a unique smell (which some find lovely and others find bothersome) thus a requirement for healthy workspace ventilation, and a drying time that usually takes exponentially longer than other mediums (although, as mentioned above, this is considered a desirable trait by some).
Which ever medium you choose, your technique and creativity will determine its beauty. Since art supplies are fairly affordable compared to other lifelong hobbies, try experimenting with multiple mediums, maybe even painting the same thing with all 3 and examining the different pros and cons, drying times, etc.