These Help pages can be downloaded here with the Winning Bridge Shareware game for Microsoft Windows 98, ME, 2000 and XP.
If you would rather read a book, take a look at the Help Index page for some suggestions.
Agreeing a Suit
To play in a suit the partnership should hold at least 8 cards in the suit between them. If a player has shown 4 cards in a suit, you should hold 4 cards to support them, similarly the holdings should be 5 - 3, 6 - 2, 7 - 1. If you cannot support your partner's suit and they have not supported your suit, try bidding a second suit to look for a fit.
Do not assume that your suit is better than your partner's. If you opened and rebid your suit, when your partner rebids their own suit it almost certainly denies that they hold 3 cards in your suit. If you hold 3 of his suit it might be best to show your support even if you hold a good 6 card suit.
If your suit is a minor suit and your partner's suit is a major and you hold support, it might be best to play in your partner's suit since it requires one less trick to make game. If your minor is strong your partner may well be able to make its tricks once trumps have been drawn.
It might be worth risking a no trump contract if there is no obvious trump fit, even if you have an unbalanced hand.