Opening at Higher Levels
You're now an expert — or close, anyway — on two-level openers, weak ones and the strong one. So what does it show when you open at the three level or higher?
In the modern game of bridge, three-level opening bids are reserved pretty much for long suits and weak hands. A typical opening bid of 3 ♦, for example, would look like this:
♠ 4
Is that scary to you? You have only 5 HCP, after all, and you voluntarily jacked yourself up to the three level. But what if your opponents double?
Well, they might double, but if you always play it safe, you'll lose a lot more than you win. Remember, it's a bidder's game and it pays to put pressure on the opponents whenever you can. One way of doing that is to jump the level of the bidding way on up there when you have a reasonable long suit.
Trumps Equal Tricks
Note that the diamond suit had a sequence from the queen to the 8. That means that if you get to play diamonds, that suit is going to take a lot of tricks. It also means that neither opponent will have a terribly robust holding in the suit, making it more difficult for them to nail you with a double. Don't forget, too, that if the HCP are distributed relatively evenly among the other three hands, your partner will have some goods to help you out. So don't shy away from your right to eat up the opponents' bidding space just because you are weak. Heck, you're supposed to be weak.
It's fair to have a better suit than QJ10, etc. You can do it with KQJ10, AKJ, AQJ … whatever, as long as your suit will be a source of tricks if it's trumps — and you don't have a lot of high cards outside your suit.
Position Counts
Believe it or not, the best place to go sailing out there with a weak bid at a high level is in the third seat. The next best spot is first seat. Can you figure out why?
In the third seat, you know you're not robbing bidding space from your partner because she already said she didn't have a great hand when she passed as dealer. Your right-hand opponent isn't loaded either. So what does that mean? Yep, the fellow sitting there licking his lips has the balance of power, so you want to take away as much bidding space as you can.
In fourth seat, it's very rare to show a weak hand with a long suit. In such a case, you would simply pass the hand out and start over. If you're weak and partner can't open, how much can you make, after all? Just pass it out and avoid a minus score.

