(MONEY Magazine) – When shopping for a financial planner or a stockbroker, ask about the types of investments that would be suitable for you. If the adviser suggests ones that you think are too risky, overly sophisticated or untimely, find another pro. What follows is a guide through a thicket of investments that you should be wary of today: Collectibles. If you are fond of stamps, coins, antiques or art, by all means collect them. But unless you are truly knowledgeable about collectibles, don't buy for profit. It's hard to make money with them because you buy collectibles at retail and sell at wholesale. Never, ever buy a collectible based on a pitch over the phone by a salesman you don't know. Commodities. The same rule of thumb for playing Las Vegas applies to investing in commodities, such as corn, wheat and hog bellies, and commodity funds: put up no more than you can afford to lose. Only professional commodity ! speculators win big with any regularity, and even their records are rarely impressive. Corporate bonds. Until a few years ago, the bonds of blue-chip companies were quite safe. But the leveraged-buy-out (LBO) fever has made all corporate bonds much riskier. In an LBO, a company takes on additional debt, straining it financially and pushing down the credit rating and value of its bonds. For example, when RJR Nabisco became a buy-out target in late 1988, its A-rated bonds suddenly started trading like BB-rated ones. Prices fell 17% the day the proposed buy-out was announced. Because of the junk glut, many money managers advise small investors to stay out of corporates altogether for fear that defaults in low-rated issues might drive down the prices of all corporate bonds. Gold bullion and coins. Like other precious metals, gold pays no dividends and generally increases substantially in value only when investors expect high inflation. Although the inflation rate has been rising, few economists expect prices to go up by more than 6% a year anytime soon. So there's little reason to buy gold. Hybrid unit trusts. These gimmicky, broker-sold securities combine into one package investments that have guaranteed returns (such as zero-coupon bonds) with others that can be quite volatile (such as gold coins). Supposedly the low risk of the bonds offsets the high risk of the coins. What this really means is that you will not lose any money -- not much of a guarantee. You can get the same combination of risks, usually for lower commissions, by buying each investment separately. The hybrid often comes with sales charges of 3.5% or so, which can be at least half of a percentage point more than total fees for the individual investments. Penny stocks. Some fast-talking brokers sell these speculative securities over the phone for less than $10 a share. At best, they are shares in new companies with little or no earnings history. At worst, they are investments in fictitious enterprises. Ever heard of the self-chilling beverage can? In that con, pulled in 1986, investors snatched up more than 1 million shares -- at 10 cents to $3.50 each -- in a bogus company called Laser Arms. So far, 20 people have been convicted in the scam, but the only recourse for the bilked investors is to sue the perpetrators of the fraud. Public real estate limited partnerships. These programs are registered with the Securities and Exchange Commission and are sold by brokers and financial planners for minimums of $5,000 or so. They pool investors' money to buy or develop properties such as apartments, office buildings and shopping centers. If all goes well over the five- to 15-year lives of the deals, investors receive a portion of the rents and capital gains from the sale of the buildings. But the price of admission to a partnership is exorbitant. Invest $10,000 in a typical program, and $1,500 to $2,500 of your cash -- 15% to 25% -- will go for fees and commissions. Fees for tax-sheltered, low-income housing and historic rehabilitation partnerships can equal 40% to 50% of your investment. In addition, limited partnership units are hard to sell before a program dissolves, and even then you may get only 50% of their fair market value or even less.