I've been using a system that is quite similar to sayc lately, but there are some differences. Here's a little information about this system. I intend to make a more complete system eventually, but this will have to do for now.
Openings
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1 of a suit
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I will open with 12 hp unless I have a very good reason not to. I might open with less than 12 hp if the distribution allows it. With a 5- or 6 card suit, I open with the longest suit. With equal length I open with the highest suit. I don't open 1h/1s unless it's at least a 5-card suit. I don't open 1d unless it's at least a 4-card suit. This means that 1c might be a 2-card suit. If I open 1c with less than 4 clubs, I have a NT-distribution. I will normally show this on my next bid.
NT
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I use NT-openings to limit the strength of my hand and tell about my distribution at the same time. The distributions that are candidates for a NT-opening are 4-3-3-3, 4-4-3-2 and 5-3-3-2. 1NT means 15-17 hp. 2NT means 20-21 hp. 3NT means that I have enough to try to go for game directly. This usually means at least 24 hp, and enough stoppers. I have actually never had a good enough hand to consider this opening, though.
2c
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2c is an artificial opening, showing 20 or more hp. I expect the answer 2d with less than 5 hp. With more, the answer should be a normal bid.
2dhs
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Other than 2c, any jump opening in a suit is weak. I'll normally have 6-9 hp after a weak opening. I will be relatively strong in the opened suit. This will usually be a 6-card suit with two honours at the 2-level, 7-card suit with two honours to open at the 3-level. I might not make a weak opening if there's a chance that my partner has enough points for game.
Responses
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Response to 1 of a suit
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I suppose this is quite similar to sayc. I normally need at least 6 hp and a 4-card suit to bid 1 of a higher suit. When I have 6-9 hp, no suit with more than 3 cards that can be bid at the 1-level and no support in the opened suit, I bid 1NT. I will make a simple support in the opened suit with 6-9 hp, jump support with 10-11 hp. With a good distibution, I might go to game in a major suit. I might not support directly if I think that another bid is more beneficial. To bid a suit at the 2-level, I require at least 10 hp. 2NT shows enough for game. 3NT is a sign-off. A jump in another suit is not a slam invitation. It's a weak jump with less than 6 hp.
Response to 1NT/2NT
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I often use Stayman and transfers. I'm familiar with a transfer to a minor, but use it seldom myself. Other responses are 2NT that invites to game without any 4-card or better major. 3NT is a sign-off. I'll get back later with slam-inviting responses.
Response to 2c
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2d with less than 5 hp. Other responses are natural. I'll comment more on them later
Response to a weak opening
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If I have enough points for game, I'll go to game. If not I'll pass or make simple support to obstruct the opponents. I'll seldom bid another suit, so don't automatically make a weak opening when you have four cards in one of the majors.
More to come...
