Bidding over opponent's preempts

Bidding over the Opponents’ Preemptive Openings

Overcall (rather than double) if you have 17 or fewer points and a decent 5-card suit.
Use the Rule of Seven to decide if your overcall is “safe”. Try to imagine an “ordinary” (not perfect) 7 points in partner’s hand. If you could make your bid opposite that hand, you should overcall.
Double (instead of overcalling a minor) if you have 3+-card support for unbid majors.
Over the opponent's opening 3-bid, choose 3NT (instead of doubling or overcalling a minor) if you have 15+ points and stoppers in the opponent's suit.
All notrump overcalls show notrump hands, not minors.
Over a Weak 2-bid, use a jump to 3NT to show a good hand and a running suit. This jump usually denies takeout-double shape (you may be extremely short in an unbid suit). With a strong balanced hand, double first, then bid notrump.
All jumps are strong. A jump overcall (2H by RHO - 3S by you) forces to game and asks partner for a cuebid. Remember the rule: “You can’t preempt a preempt.”

Stretch to compete if you’re short in their suit.
For doubles and overcalls, mentally add an ace to your hand, then choose the same bid you would make in direct seat.
Stretch a bit more to make a takeout double if you're short in their suit and the vulnerability is favorable (they’re red and you’re not). Partner may have a trump stack and convert your double to penalty.

Over an opponent's Weak 2-Bid in a major (opening of 2H or 2S), here are the meanings of "Leaping Michaels" direct overcalls:

Jump in a minor (2S-4C or 4D) = That minor + the other major, strong 5-5 or better.
Direct cuebid (2H-3H) = Asks for stopper for notrump.
Jump cuebid (2H-4H, 2S-4S) = Both minors, strong 5-5 or better.

Over an opponent's Weak 2D opening: A jump cuebid (2D-4D) = Both majors.

Your action:	Over their Weak 2-bid:	Over their 3-bid:
Simple overcall	10-17 points 5+ card suit	12-17 points 6+-card suit or strong 5+ cards
Double	12+ points, shortness in their suit 3-4+ cards in all unbid suits OR 18+ points and a long suit	14+ points, shortness in their suit 3+ cards in all unbid suits OR 19+ points and a long suit
Double, then bid a suit	17+ points Strong 5+-card suit	18+ points Strong 5+-card suit
Jump to 3S over 2H opener	16+ points, very strong 6+-card suit
Jump to 4 of a minor	(2H/2S - 4C or 4D = Leaping Michaels Strong 5-5 or better in bid suit & other major	3C-4D = Strong one-suiter, asks for cuebid
4H or 4S	16+ points and a strong 6+-suit	16+ points and a strong 6+-suit
Cuebid (2H-3H)	Usually a strong 1-suiter Asks for stopper for notrump	Minor (3C-4C) = Strong, at least 5-5 in both majors Major (3H-4H) = Strong, at least 5-5 in spades and a minor
Jump cuebid	Leaping Michaels (2H-4H, 2D-4D)
2NT	14-18 points balanced with stopper(s)
Double, then rebid NT	18+ points balanced with stopper(s)	22+ points with stoppers and support for unbid suits
3NT	16+ points with stopper and a long running minor	16-22 points with stopper(s) May be a running minor and stopper(s)

Pass = 0-7 points (remember the Rule of Seven -- partner is already counting on you to hold an "average" 7-point hand).
Single raise of partner’s suit (2H-2S-P-3S) = 8-10 points and 3+-card support.
Cuebid of their suit (2H-2S-P-3H) = Strong raise of partner’s suit, forcing to game.
Jump in another suit (2H-2S-P-4C, 4D or 4H) = Splinter raise (slam-try values, trump support and a singleton in the bid suit)
New suit (3C-3H-P-3S) = Forcing, 5+-card suit.
Double (if RHO raises his partner's suit: 2H-2S-3H-DBL) = Responsive double, showing values (10+ points), length in the unbid suits, 2 or fewer cards in partner’s suit.

Make your “normal” value bids:
   With a weak hand (0-8 points), make a low-level bid in your longest unbid suit (2H-DBL-Pass-2S, 3C or 3D).
   Jump to 3 of your suit with 8-10 points and a 5-card suit (2H-DBL-Pass-3S).
   Jump to game in your suit with 11+ points.
Consider adding the Lebensohl convention to your system to improve your bidding accuracy when you hold 0-11 points.
If you’re considering passing the double for penalties, you need long, strong trumps. Evaluate by using the Rule of Nine:
Add: The level of their contract + # of your trumps + # of your trump honors (10 and higher).
If the total is 9 or more, you can consider passing for penalty.

Play “system on” – 3C is Stayman, 3D & 3H are transfers.
If partner jumps to 3NT (2H-3NT), he could be short in an unbid suit, so don't insist on playing in your long suit. Unless you have slam-try values, pass.