I prefer to play something close to the Standard American Yellow Card convention. This consists of:

• 5 card majors,
• better minor (though usually bid 1 with 4-4 in the minors, and usually bid 1 with 3-3 in the minors)
• 1NT = 15-17 high card points and 4-4-4-3, 4-4-3-2, or 5-3-3-2 distribution
• 2NT = 20-21 high card points, 3NT = 25-27 high card points and 1NT distribution
• 2C = 22+ points, artificial and forcing (2D response indicates weak hand)
• Weak 2D, 2H, 2S promising 8-12 points and a 6+ card suit
• Stayman and Jacoby Transfers over 1NT, 2NT, 3NT opening hands
• 2S over 1NT = "minor Stayman": opener bids 2NT with no 4-card minor, bids 3 of a minor with 4 cards otherwise.
• Gerber: 4C as a jump shift over notrump or after both players have bid in notrump is ace-asking: 4D=0 or 4, 4H=1, 4S=2, 4NT=3. 5C after Gerber 4C asks for Kings.
• Blackwood: 4NT except when bidding player has just bid NT asks for aces. 5C=0 or 4, 5D=1, 5H=2, 5S=3. 5NT after Blackwood 4NT asks for Kings.
• Slam Cue Bids: Bid in a new suit after agreeing on a suit shows control: Ace/void or King/Singleton, in that order. Example: 1H - 3H - 3S shows spade control. 1H - 3H - 4C - 4D - 4S shows King/Singleton control in Spades, since 3S could have been bid over 3H.

However, if my partner doesn't specifically agree to the above, I play:

• 5 card majors / better minor as above,
• 2C = strong, artificial
• 1NT = 15-17, 2NT = 20-21, 3NT = 25-27 and even distribution
• Stayman
• Weak 2s
• Blackwood, Gerber
• No transfers