CNN Money's "Ask the Expert" column takes on professional money managers.
The basic question is whether a science teacher should ditch his collection of mutual funds for a professional money manager that will take 2% of assets as his fee. The Expert says it's likely that he'll lose out since he'll be paying 1% more annually than he is paying now for a service he could do himself.
He does have a good point. The "lifestyle" funds that he mentions are a great tool for those that don't want to deal with rebalancing and tracking their own portfolio of mutual funds. These funds are far from perfect (and often way more conservative than they should be) but for a market-phobe it's a decent tradeoff of risk and return.
Another option would be to pick up either Kiplinger Personal Finance or Money when they do their annual Mutual Fund guides and use those model portfolios as guides for setting up your own portfolios.
Stay away from money managers unless you have enough money that you absolutely need to diversify into commodities, real estate, and the like. If you're asking yourself if you meet that test, you probably don't. Spending a few hours reading one of the publications above should give even the market novice a good head start.
If that still isn't an option, going to a fee-only personal financial advisor would work as well. They can guide you to a diversified portfolio without taking a percentage off of the top every single year.