Investing in art is trickier than the other categories, because no formal market for it exists. There's no guarantee that a painting you buy today will interest anyone else enough to purchase it in the future.
So if you're going to invest in art, the first rule is to buy something you will enjoy seeing on your wall, as it might remain there for the rest of your life. Once you find something you like, do enough research and consultation to feel confident that what you're buying has a good chance to increase in value over the years.
Keep in mind that art generally doesn't make sense as a short-term investment because commissions to buy or sell art through a dealer or at an auction can run up to 20 percent.
A good place to find art is at a reputable show. Big cities such as New York have several per year. If you make it to a New York show, you may be able to find dealers there who are located near you.
As for research, you can find catalogs, sales prices and all kinds of other information on the Internet. Curators at your local museum also can be a good source of information. If you can establish a relationship with a trustworthy dealer, he or she can give you a wealth of valuable information.