Summertime is no more, which means ...

Football's back. (Oh, and the kids are back at school, too.)

Which got me to thinking: A good equity portfolio looks exactly like a good offensive football team. (I say "offensive" because Fools don't invest defensively.) Let me explain.

Blue-chip building blocks
As I've said elsewhere, tomorrow's industry leaders are largely unknown today. Identifying them -- and then buying and holding them -- can give you the highest possible returns. But ...

A team of high-flying glamour stars is a chemistry experiment gone awry. Every stock should play a role that will give your portfolio the necessary balance. It should start with a heavy-duty foundation -- let's call it the offensive line. The O-line anchors the team. It's involved in every single play. Think GE (NYSE:GE) or ExxonMobil (NYSE:XOM), which sport the two largest market caps in the world. Throw in other dependable stalwarts such as Bank of America, PepsiCo (NYSE:PEP), and BP (NYSE:BP), and you've rounded out the blue-chip foundation. Or you could get 'em all by investing in a solid index-tracking fund -- a very Foolish move, by the way -- like the Vanguard 500 Index.

Most NFL teams also play with a sixth scrimmage-hugger, a down lineman who swings between blocking one play and grabbing passes the next. We're talking about the tight end. Think Harley-Davidson. It's steady, but a little on the edge. It anchors your portfolio and gives you some growth pep.

That's a rock-solid roster. But I've met people whose entire portfolio is one big offensive line. They're typically older investors who've put up uninspiring returns for years through mutual funds or bonds or yesterday's players. Their quarterback is as big as the guy he takes snaps from; you couldn't tell their flanker and their tackles apart in a brightly lit room. They don't lose money; they just don't win many games. Can you say Arizona Cardinals?

The stars
While the blue-chippers anchor the team, they aren't the entire team.

I also know investors whose savings are invested purely in lightweights and scatbacks. Underestimating the importance of beef in the trenches, these people end up with a list of speedsters whose lack of size and speed make them highly susceptible to injury. The Indianapolis Colts come to mind.

Your team needs to be rounded out with a few dependable growth stocks -- we'll call them our running backs. Let's put an eBay (NASDAQ:EBAY) at running back and a Microsoft -- big, burly, slow, but steady and with the potential for a big play -- at fullback.

Calling plays on this team is It's an aging star whose best years are probably in the past. Its importance to the success of the overall team is inflated by the media. But it touches the ball on every play, and it will occasionally make a huge play for you.

That's a solid lineup. It will win you many games, and let you sleep soundly at night.

But success in investing -- as in football -- requires big plays. Enter the higher-risk, higher-reward wide receivers -- after all, you need a few speedy guys to throw the bomb to from time to time. In our Motley Fool Stock Advisor portfolio, I've recommended several of these speedsters over the years, and they are the perfect complement to the muscle up front.

Let's line two of our picks up at wide receiver: Activision (NASDAQ:ATVI) and DreamWorks Animation (NYSE:DWA). Since its recommendation in September 2003, Activision is up more than 115%. In fact, after I recommended the business to Stock Advisor subscribers, the shares nosedived. Several months later, I re-recommended the company at a lower price, and the stock has yielded a 315% return from those lows. DreamWorks Animation is a recent recommendation, and while it hasn't yet shown us its breakaway speed, I think it has plenty of room to run in the future.

"If it doesn't matter who wins or loses, why do they keep score?"
The great Vince Lombardi understood the nature of sports and gaming. Exactly who would your portfolio "line up" against every weekend? Simple. The indexes.

Every month, I also line up against my brother in Stock Advisor. We each recommend one company to subscribers. Whichever pick "wins" (i.e., has a better return) is bolded on our scorecard for all our subscribers to see. (A little brotherly competition, a la Peyton vs. Eli?)

So when you're lounging on the couch this Sunday watching your favorite team, ask yourself: Is my portfolio built to win?

The brothers compete ... you profit. To date, David and Tom's Stock Advisor selections are beating the S&P 500 by almost 40 percentage points. If you'd like to see how they're doing it,the brothers Gardner are offering a free 30-day trial membership. A trial includes access to every pick ever made in the newsletter, every issue in our archives, and our Foolish community of message boards. See what all the fuss is about by clicking here.

Fool co-founder David Gardner owns shares of, eBay, and Microsoft., eBay, Activision, and DreamWorks are Stock Advisor recommendations. The Motley Fool has a disclosure policy.