Bigger is usually better. Dollar cost averaging into large, quality stocks is the recipe for compounding your money steadily into an eventual fortune. I trust Bill Gates with my money, and I realize he knows more than I do. Stick with the sure thing. Gambling is for Las Vegas, not your retirement.
Some diversity is good, but too much is bad.
They are outdated. This also lowers commissions and fees. Having too many stocks can be worse than too few. For more on how to find such companies, check out the Rule Maker Criteria. Expensive stocks are expensive for a good reason, so don't rule them out simply on that basis.